Facsimile system operable in toner save mode, depending upon type of original image data

ABSTRACT

A recording apparatus wherein an original image is recorded in a matrix of dots by applications of a toner tolocal spots on a recording medium, and which includes a non-toner-save controller for recording the original image in a non-toner-save mode, a toner-save controller for recording a toner-save image in a toner-save mode such that the toner-save image generated on the basis of the original immage has a lower density of image dots than the original image, and a mode selector for activating one of the non-toner-save controller and the toner-save controller to select the corresponding non-toner-save or toner-save recording mode, on the basis of the type of the original image data.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a facsimile system having an imagerecorder or printer capable of recording an image using a toner.

2. Discussion of the Related Art

In a recording or printing apparatus wherein an image is recorded in amatrix of dots by deposition of a toner at selected ones of local spotscorresponding to the picture elements of the dot matrix, it is desiredto save the toner, namely, minimize the amount of consumption of thetoner. An example of an image recording apparatus which is operable in atoner save mode for reducing the toner consumption is disclosed inJP-A-2-144574 (published in 1990), which includes (a) a recordingportion for recording an image with a toner on a recording medium in amatrix of dots, (b) a non-toner-save control portion for controlling therecording portion in a non-toner-save mode according to original imagedata representative of an original image to be reproduced, (c) atoner-save control portion for controlling the recording portion in atoner-save mode according to toner-save image data representative of atoner-save image whose density of image dots is lower than that of theoriginal image and which is recognizable as an image similar to theoriginal image, and (d) an operator-controlled mode selector switch forselecting one of the non-toner save and toner-save control portions toeffect recording in the corresponding one of the non-toner-save andtoner-save modes.

The toner-save control portion for controlling the recording portion inthe toner-save mode includes image-dot determining means fordetermining, on the basis of the original image data, whether an imagedot is formed at each local spot or picture element position of thematrix. The image-dot determining means is adapted to generatetoner-save image data so that where image dots are to be formed at twoor more successive local spots in a line (row) or column of the dotmatrix according to the original image data, the image dots to beactually formed are omitted at every other local spot of thosesuccessive local spots. If the image dots are to be formed according tothe original image data at three successive local spots in a certainline, for example, the image dot is actually omitted at the intermediateone of the three successive local spots. The omission of the image dotsin a line or column is effected uniformly over the entire line orcolumn.

Thus, the image-dot determining means of the toner-save control portionof the apparatus described above is arranged to perform a dataprocessing operation for each local spot or picture element position ofthe dot matrix, to determine whether an image dot is actually formed ateach local spot according to the toner-save image data.

When the non-toner-save control portion is selected by manual operationof the mode selector switch, the recording portion is controlled in thenon-toner-save mode according to the original image data. When thetoner-save control portion is selected by the mode selector switch, therecording portion is controlled in the toner-save mode according to thetoner-save image data generated as described above.

However, the user of the recording apparatus must manipulate the modeselector switch to select the toner-save or non-toner-save mode. Thismanipulation is cumbersome.

The selection of the non-toner-save or toner-save recording mode shoulddesirably be made depending upon the type of the original image data.However, the user of the apparatus does not necessarily recognize thatthe recording mode should be selected depending upon the type of theoriginal image data. Further, the user does not necessarily know thetype of the original image data used to reproduce an image, and is notalways able to select one of the recording modes that better suits thetype of the original image data.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an imagerecording apparatus which is automatically placed in a toner-save modewithout user's manipulation of a mode selector switch, depending uponthe type of original image data representative of an original image tobe reproduced.

The above object may be achieved according to the principle of thepresent invention, which provides a recording apparatus comprising (a) arecording portion for effecting a recording operation on a recordingmedium in a matrix of dots by selective application of a toner to localspots on the medium, according to original image data representative ofan original image to be reproduced, the local spots corresponding topicture elements of the dot matrix; (b) a non-toner-save control portionfor controlling the recording portion according to the original imagedata to form the original image in a non-toner-save recording mode; (c)a toner-save control portion for controlling the recording portionaccording to a toner-save image data to form a toner-save image in atoner-save recording mode, the toner-save image having a lower densityof image dots than the original image and being recognizable as an imagesimilar to the original image, the toner-save control portion generatingthe toner-save image data on the basis of the original image data; and(c) mode selector means for activating one of the non-toner-save controlportion and the toner-save control portion to select a corresponding oneof the non-toner-save and toner-save recording modes, on the basis of atype of the original image data.

The mode selector means may comprise means for detecting the type of theoriginal image data, for example, gray scale data, image datarepresentative of an image including a relatively large number ofspecial characters (e.g., numerals, symbols and graphicalrepresentations) other than letters, or image data representative of arelatively minute image such as an image consisting of small characters.

In the present recording apparatus, either the non-toner-save controlportion or the toner-save-control portion is automatically selecteddepending upon the specific type of the original image data, so as tocontrol the recording portion according to the original image data inthe selected non-toner-save or toner-save recording mode. Therefore, thepresent apparatus does not require the user to know the type of theoriginal image data and manipulate a mode selector switch to select thenon-toner-save or toner-save recording mode. Accordingly, the user isnot required to know the subject matter of the original image data.

When the toner-save control portion is selected and activated by themode selector means, the recording portion is controlled according tothe toner-save image data in the toner-save recording mode to form thetoner-save image. In the toner-save recording mode, the amount ofconsumption of the toner is smaller than in the non-toner-save recordingmode in which the recording portion is operated according to theoriginal image data. The toner-save image data are formulated so thatthe toner-save image is recognizable as an image similar to the originalimage.

In one preferred form of this invention, the mode selector meanscomprises selecting means for selecting the non-toner-save recordingmode when the original image data are gray scale data. If imagerecording is effected in the TONER-SAVE recording mode according to thegray scale image data, there may arise a problem relating to theuniformity and gradation of the image density. To avoid this problem,the non-toner-save recording mode is selected when the original imagedata are recognized as the gray scale data.

In the above form of the invention, the mode selector means may comprisegray scale data recognizing means for recognizing the original imagedata as the gray scale data which represent said original image in adither matrix. In this instance, the selecting means selecting thenon-toner-save recording mode when the gray scale data recognizing meansrecognizes the original image data as the gray scale data.

As indicated above, the gray scale image data are formulated to definean image in a dither matrix, namely, to represent a gray scale image byonly one of two levels "white" and "black" corresponding to dot databits "0" and "1". Accordingly, the logical values of the adjacent dotdata bits obtained from the gray scale data tend to change relativelyfrequently. In other words, a unit volume of the dot data obtained byconversion from the gray scale data have comparatively large number ofpairs of adjacent bits which have different logical values "0" and "1".Therefore, a determination as to whether the received image data aregray scale data can be effected by checking if the number of such pairsof adjacent bits per unit volume of the dot data obtained from thereceived image data is larger than a predetermined threshold value.

In view of the above analysis, there is provided one advantageousarrangement of the above form of the invention wherein the originalimage data are dot data comprising data bits representative of presenceor absence of image dots at the local spots corresponding to the pictureelements of the dot matrix, and wherein the selecting means comprisesmeans for recognizing the original imaeg data as the gray scale data ifthe number of changes of adjacent ones of the data bits of the dot dataper unit volume of the dot data is larger than a predeterminedthreshold.

In another preferred form of this invention, the matrix of dots isdefined by a plurality of parallel lines extending in a first direction,and a plurality of parallel columns extending in a second directionintersecting the first direction, and the toner-save control portiongenerates the toner-save image data which include non-imaging data setsfor inhibiting the application of the toner to all of the local spotswhich are arranged along selected ones of the parallel lines and/or theparallel columns of the matrix of dots, so that the toner-save image ispartially defined by blank lines and/or blank columns of pictureelements which correspond to the respective non-imaging data sets. Thetoner-save control portion controls the recording portion in thetoner-save recording mode according to the toner-save image data whichinclude the non-imaging data sets. The blank lines and the blank columnsappear in the toner-save lines at respective lines and columnsrepresented by at least one of equations L=M×m+p, where "L" representsthe blank lines and blank columns, "M" is an integer not smaller than"2", "m" is an integer which increases from "0" in increment of "1", and"p" is an integer betweeen "1" (inclusive) and "M" (inclusive).

In the above preferred form of the invention, the toner-save image datagenerated by the toner-save control portion include the non-imaging datasets for forming respective blank lines and/or blank columns along whichno image dots are formed at the respective local spots by application ofthe toner, whereby the toner consumption is reduced in the toner-saverecording mode. The blank lines or blank columns of the toner-save imagecorrespond to the selected lines or columns of the matrix of dots, whichare represented or determined by at least one integer expressed by(M×m+p) defined above, which will be described in detail.

In the above form of the invention, there are three different cases. Inthe first case, only the blank lines are formed. In the second case,only the blank columns are formed. In the third case, both the blanklines and the blank columns are formed. In the interest ofsimplification, the following description refers to the blank lines. Thesame description substantially applies to the blank columns. Forimproved data processing efficiency, however, it is generally desirablethat the non-imaging data sets included in the toner-save image dataconsist solely of the data sets for the blank lines.

Where the positions of the blank lines is determined by a singleequation L=M×m+p, a selected one of two or more successive lines is madeblank. For example, the blank line appears every second line of the dotmatrix if the value of the integer "M" to define a single equationL=M×m+p is equal to "2", and every third line of the dot matrix if thevalue of the integer "M" is equal to "3". That is, the integer "M"represents the number of successive lines of the dot matrix which belongto each group including one blank line. If the integer "M" is equal to"4", for example, one of the four successive lines of each group is madeblank. For example, the fourth line of the four successive lines is madeblank where "p" is equal to "4".

Where the value of the integer "M" is "3" or more, two or more equationsL=M×m+p may be used, so that each group of successive lines may includetwo or more blank lines. If the integer "M" is "3", two equations LM×m+p may be used, for example. In this case, any combination of twolines selected from each group consisting of three successive lines maybe made blank. For example, one equation is L=3×m+1 and the otherequation is L M×m+p. Namely, the integers "p" has different values "1"and "2" in the two equations (3×m+p). Similarly, the first and thirdlines, or the second and third lines may be made blank, by usingdifferent values of the integer "p".

Where the value of the integer is "4", two or three equations L=4×m+pmay be used. If the image dots are formed along the first line of eachgroup of four successive lines, the following lines may be made blank,for instance: (i) second, third and fourth lines ("p"=2, 3, 4); (ii)second and fourth lines ("p"=2, 4); (iii) second and third lines ("p"=2,3); and (iv) third and fourth lines ("p"=3, 4).

The value of the integer "p" in each equation L=M×m+p may be eithervariable or fixed. Where the value or values of the integer "p" is/arefixed, it is not necessary to determine the value or values of theinteger "p" depending upon the type of the original image data, forexample. In this case, the second line of each group is made blank ifthe integer "p" in the single equation L=2×m+p is "2", and the secondand third lines are made blank if the integer "p" in one of the twoequations L=3×m+p) is "2" while the integer "p" in the other equationL=3×m+p is "3". The second, third and fourth lines are made blank wherethe values of the integer "p" in the three equations (4×m+p) are "2","3" and "4", respectively.

It is possible to determine the value of the integer "M" used in theequation or equations L=M×m+p, depending upon the situation, forexample, depending upon the type of the original image data. Forinstance, the value of the integer "M" is selected to be either "2" or"3". Further, if the value "M" in two equations L=M×m+p used is "3", thevalues of the integer "p" may be suitably determined, for example, "2"and "3". In this case, the second and third lines are made blank.

In the present preferred form of the invention in which the toner-saveimage data include the non-imaging data sets for forming the blank linesand/or blank columns, the toner-save image data can be more efficientlyand economically generated on the basis of the original image data,because the present arrangement does not require conventionally effecteddata processing to determine whether an image dot should be formed ateach of the local spots in each of the parallel lines or parallelcolumns of the dot matrix. For example, the non-imaging data sets may becommands which merely cause a line feeding incremental rotation of aphotosensitive drum of the recording portion, or dot data sets whosebits are all "0" commanding the absence of image dots at the respectivelocal spots.

In one advantageous arrangement of the above preferred form of theinvention, the mode selector means comprises image minuteness detectingmeans for determining whether a degree of minuteness of the originalimage represented by the original image data is larger than apredetermined threshold value, and the mode selector means activates thenon-toner-save control portion if the image minuteness detecting meansdetermines that the degree of minuteness of the original image is largerthan the predetermined threshold value.

Where the original image data are dot data whose bits represent thepresence or absence of image dots at the local spots corresponding tothe picture elements of the dot matrix, the numbers of the successivelocal spots at which the image dots are present or absent indicate thedegree of minuteness of the original image, for instance, the size ofthe characters of the original image. More specifically, the minutenessof the original image increases with a decrease in the numbers of thesuccessive local spots at which the image dots are successively presentor absent. Thus, the image minuteness detecting means may determine theminuteness of the original image on the basis of the numbers of thesuccessive local spots at which the image dots are present or absent.Where the original image is relatively minute, the recognition of theoriginal image tends to be difficult if the original image is recordedin the toner-save mode, and is therefore desirably recorded in thenon-toner-save mode. said toner-save control portion determines at leastone of a value of the integer "M" and the number of the above-indicatedat least one equation L=M×m+p, on the basis of said degree of minutenessof the original image determined by said image minuteness detectingmeans.

In the above arrangement, the toner-save control portion may be adaptedto determine the number of the above-indicated at least one integerexpressed by (M×m+p) and/or each value of the at least one integer, onthe basis of the degree of minuteness of the original image determinedby the image minuteness detecting means. As indicated above, theintervals of the blank lines, for example, are determined by the integeror integers referred to above and the number of the integers. Where asingle integer is used, the ratio of the blank lines ("toner-saveratio") decreases with an increase of the value of the integer. Wheretwo or more integers are used, the toner-save ratio increases with anincrease of the number of the integers. The toner-save ratio may be highwhen the minuteness of the original image is relatively low, forexample, when the size of the characters of the original image isrelatively large. The toner-save ration is desirably reduced as theminuteness of the original image increases, to maintain the legibilityof the minute image.

The toner-save control portion may be arranged to determine the numberof the above-indicated at least one integer and/or each value of the atleast one integer, on the basis of toner save information received froman external device from which the original image data are received. Inthis instance, the apparatus may further comprise character data memorymeans for storing coded character data as the original image data, andimage data generating means for generating binary image data on thebasis of the coded character data, so that the non-toner-save controlportion controls said recording portion according to said binary imagedata in said non-toner-save recording mode. The mode selector meanscomprises character recognizing means for recognizing a type ofcharacters represented by the coded character data, and the modeselector means activates one of the non-toner-save control portion andthe toner-save control portion, depending upon the type of thecharacters recognized by the character recognizing means.

In the above arrangement, the character recognizing means is adapted torecognize the type of the characters as represented by the codedcharacter data stored in the character data memory means, morespecifically, determine whether the characters are relatively simplecharacters such as the alphabetic letters or Japanese "kana" or phoneticletters, or relatively complicated characters such as Chinese letters,or whether the characters are relatively large characters or relativelysmall characters. The mode selector means selects the non-toner-savecontrol portion or toner-save control portion, depending on therecognized type of the characters.

For instance, the character recognizing means may comprise charactersize determining means for determining whether a size of the charactersis larger than a predetermined threshold value. In this case, the modeselector means activates the toner-save control portion if the size ofthe characters is determined to be larger than the threshold value. Whenthe character data represent relatively large characters, the recordingin the toner-save mode will not significantly influence the legibilityof the recorded characters.

The character recognizing means may comprise special character detectingmeans for detecting special characters other than letters, in thecharacters as represented by the coded character data. The specialcharacters may be detected by detecting the letters which are charactersother than the special characters. Since the number of the specialcharacters is generally smaller than the letters, the time required fordetecting the special characters is shorter than the time required fordetecting the letters.

The special character recognizing means may comprise ratio determiningmeans for determining a special character ratio which is a ratio of anumber of the special characters to a total number of the characters asrepresented by the coded character data. In this case, the mode selectormeans activates the non-toner-save control portion if the specialcharacter ratio is larger than a predetermined threshold value. It isnoted that the letters can be guessed from the context of the recordedimage, even if the letters recorded in the toner-save mode are more orless illegible or partly invisible. On the other hand, it is usuallydifficult to recognize the special characters such as numerals andsymbols from the context of the recorded image, if the recorded specialcharacters are illegible. For instance, the numerals "3" and "8" or thenumerals "6" and "8" cannot be easily distinguished from each other ifthese numerals are not clearly visible due to the reduced density ofimage dots of the image recording in the toner-save mode. Accordingly,it is desirable to record the special characters in the non-toner-savemode.

If the threshold value of the special character ratio is close to zero,the non-toner-save recording mode is selected (with the non-toner-savecontrol portion being activated), even if the number of the specialcharacters in the total number of the characters is considerably small.If the threshold vale is about 0.5, the non-toner-save recording mode isselected if the number of the special characters is more than about 50%of the total number of the characters.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and optional objects, features, advantages and technicalsignificance of the present invention will be better understood byreading the following detailed description of presently preferredembodiments of the invention, when considered in connection with theaccompanying drawings in which:

FIG. 1 is a perspective view of a facsimile system incorporating animage recording apparatus constructed according to one embodiment of thepresent invention;

FIG. 2 is a side elevational view in cross section of the facsimilesystem of FIG. 1;

FIG. 3 is a side elevational view partly in cross section of adeveloping device of the facsimile system;

FIG. 4 is a side elevational view partly in cross section of a portionof the developing device of FIG. 3 at which a toner cartridge ismounted;

FIG. 5 is a plan view in cross section of a toner cartridge chamber ofthe developing device;

FIG. 6 is a perspective view showing a portion of the toner cartridge tobe received in the toner cartridge chamber of FIG. 5;

FIG. 7 is a view of a side wall of the toner cartridge chamber, taken indirection P indicated in FIG. 5;

FIG. 8 is a view of an arm attached to the side wall of FIG. 7, taken inthe direction P in FIG. 5;

FIG. 9 is a side elevational view in cross section of the tonercartridge chamber and the toner cartridge received in the chamber;

FIG. 10 is a side elevational view in cross section of the tonercartridge whose levers are pivoted;

FIG. 11 is a perspective view of a second locking device for the tonercartridge;

FIG. 12 is a side elevational view in cross section of the secondlocking device of FIG. 11 and unlocking members for the second lockingdevice;

FIG. 13 is a side elevational view in cross section of a first lockingdevice provided on a partition wall of the developing device of FIG. 3,and unlocking members for the first locking device;

FIG. 14 is a front elevational view in cross section of a residual toneramount sensor and the neighboring members of the toner cartridge;

FIG. 15 is a side elevational view in cross section of the tonercartridge;

FIG. 16 is a view indicating outputs of the residual toner amount sensorof FIG. 14;

FIG. 17 is a block diagram illustrating a control device of thefacsimile system of FIG. 1;

FIG. 18 is a view schematically illustrating an electrostatic latentimage formed on a photosensitive drum of the facsimile system;

FIG. 19 is a plan view of an operator's control panel of the facsimilesystem;

FIG. 20 is a view schematically indicating an arrangement of a RAM ofthe control device of FIG. 17;

FIG. 21 is a view schematically indicating an arrangement of a ROM ofthe control device;

FIG. 22 is a view schematically indicating an arrangement of an EEPROMof the control device;

FIG. 23 is a flow chart illustrating a TONER SAVE FLAG SETTING routinestored in the ROM of FIG. 21;

FIG. 24 is a flow chart illustrating an IMPORTANT IMAGE DATA FLAG 1SETTING routine stored in the ROM;

FIG. 25 is a flow chart illustrating an IMPORTANT IMAGE DATA FLAG 2SETTING routine stored in the ROM;

FIG. 26 is a flow chart illustrating a GRAY SCALE DATA FLAG routinestored in the ROM;

FIG. 27 is a flow chart illustrating a CONDITIONAL TONER SAVE FLAGSETTING routine stored in the ROM;

FIG. 28 is a flow chart illustrating an OPERATING CONDITION FLAG 1SETTING routine;

FIG. 29 is a view schematically showing encoded image data stored in theRAM of FIG. 20;

FIG. 30 is a view schematically showing decoded image data stored in theRAM;

FIG. 31 is a view showing a table stored in the ROM, which tablerepresents a relationship between image resolutions and controlconstants used in a toner-save recording mode of the facsimile system;

FIG. 32 is a flow chart illustrating a recording control routine storedin the ROM;

FIG. 33 is a view schematically indicating an image recorded on arecording medium in a non-toner-save recording mode of the facsimilesystem;

FIG. 34 is a view schematically indicating an image recorded on themedium in the toner-save recording mode;

FIG. 35 is a view indicating a marking recorded on the medium in thetoner-save recording mode;

FIG. 36 is a view schematically indicating an image recorded on themedium in the toner-save recording mode by a facsimile systemconstructed according to another embodiment of the invention;

FIG. 37 is a flow chart illustrating a recording control routine storedin the ROM of a facsimile system according to a further embodiment ofthe invention;

FIG. 38 is a view schematically indicating an image recorded on themedium in the toner-save recording mode in the embodiment of FIG. 37;

FIG. 39 is a view schematically indicating modified decoded image datagenerated by a control device of a facsimile system according to a stillfurther embodiment of the invention;

FIG. 40 is a flow chart illustrating a recording control routine storedin the ROM of the control device used in the embodiment of FIG. 39;

FIG. 41 is a plan view of the operator's control panel provided in afacsimile system according to a yet further embodiment of thisinvention;

FIG. 42 is a perspective view of an image recording apparatusconstructed according to another embodiment of the invention;

FIG. 43 is a side elevational view in cross section of the recordingapparatus of FIG. 42;

FIG. 44 is a block diagram illustrating a control device for therecording apparatus of FIG. 42;

FIG. 45 is a view schematically indicating an arrangement of a RAM ofthe control device of FIG. 44;

FIG. 46 is a view schematically indicating an arrangement of a ROM ofthe control device of FIG. 44;

FIG. 47 is a view schematically indicating an arrangement of an NVRAM ofthe control device of FIG. 44;

FIG. 48 is a flow chart illustrating a TONER SAVE FLAG SETTING routinestored in the ROM of FIG. 46;

FIG. 49 is a flow chart illustrating a CHARACTER SIZE FLAG SETTINGroutine stored in the ROM of FIG. 46;

FIG. 50 is a flow chart illustrating a SPECIAL CHARACTER RATIO FLAGSETTING routine stored in the ROM of FIG. 46;

FIG. 51 is a flow chart illustrating a recording control routine storedin the ROM of FIG. 46;

FIG. 52 is a view schematically indicating decoded image data stored inthe RAM of FIG. 45; and

FIG. 53 is a view schematically indicating an original image recorded inthe non-toner-save recording mode, and a toner-save image recording inthe toner-save mode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring first to the perspective view of FIG. 1, there is shown animage recording apparatus in the form of a facsimile system equippedwith a telephone. The facsimile system incorporates a facsimiletransmitter, a facsimile receiver, and a telephone receiver having ahand set 12 provided on a left side of a main body 10. The facsimilesystem has an operator's control panel 14 on the upper surface of afront portion of the main body 10, and a cassette receptacle 16 in arear portion of the main body 10. The cassette receptacle 16 is adaptedto removably receive a paper cassette 17 as indicated in FIG. 2.

The paper cassette 17 accommodates a stack of paper sheets 18. Near theinner end of the cassette receptacle 16, there is disposed an automaticsheet feeder including a feed roll 20 and a separator pad 22 whichcooperate to feed the paper sheets 18 one after another, such that theuppermost sheet 18 of the stack in the paper cassette 17 is deliveredfrom the cassette 17. The cassette receptacle 16 is partly defined by anupper wall which provides a manual sheet insertion table 24 on which asheet 18 is manually placed by the operator such that the leading end ofthe sheet 18 is located slightly above the leading end of the stack ofpaper sheets 18 in the paper cassette 17. The sheet placed on the table24 is also fed by the automatic sheet feeder. The sheet 18 placed on themanual sheet insertion table 24 is detected by a paper sensor 25 locatedabove the feed roll 20.

The sheet 18 fed by the automatic sheet feeder is transferred by a pairof transfer rolls 26 to a nip between a photosensitive drum 30 and atransfer device 32.

The circumferential surface of the photosensitive drum 30 is imagewisescanned by a laser beam by a scanner unit 34, so that an electrostaticlatent image is formed on the photosensitive drum 30. The scanner unit34 includes a laser generator 36, a condenser lens 37 and a reflectormirror 38. The laser generator 36 has a laser source for generating thelaser beam under the control of a control device 40, and a polygonmirror for deflecting the laser beam so that the photosensitive drum 30is scanned in the axial direction by the deflected laser beam. The laserbeam is condensed by the lens 37, and reflected by the mirror 38 toirradiate the photosensitive drum 30.

The photosensitive drum 30 is repeatedly scanned or irradiated alongparallel lines by the laser beams modulated according to image data soas to form an electrostatic latent image while the drum 30 is rotated.The latent image is formed in a matrix of dots corresponding to localspots or picture elements 42 (FIG. 17). The size of each dot or pictureelement 42 in a primary scanning direction (parallel to the axialdirection of the drum 30) is determined by the laser scanning speed,while the size in a secondary scanning direction (parallel to therotating direction of the drum 30) is determined by the rotating speedof the drum 30. In the present embodiment, the scanning direction androtating speed of the drum 30 are determined so that each dot or pictureelement 42 has a size of 1/8 mm in the primary scanning direction and asize of 1/15.4 mm in the secondary scanning direction, when theresolution of the image is set at a SUPER-FINE value as described below.

The photosensitive drum 30 is rotated by a drum drive motor 44 (FIG.17), which is connected to the control device 40 through a motor driver45.

The scanner unit 34 is controlled according to image data supplied fromthe control device 40 so that each laser beam corresponding to each line(row) of local spots or picture elements 42 in the primary scanningdirection is modulated such that the local spots 42 at which image dotsare formed are irradiated by the laser beam while the local spots 42 atwhich no image dots are formed are not irradiated. In the presentfacsimile system, the control device 40 provides two different kinds ofimage data, that is, non-toner-save image data used in a non-toner-saverecording mode, and a toner-save image data used in a toner-saverecording mode, as explained below in detail. The image reproducedaccording to the toner-save image data has a lower density of image dotsthan that reproduced according to the non-toner-save image data.

The electrostatic latent image is formed on the surface of thephotosensitive drum 30 by sequential scanning along successive linesaccording to a batch of image data. The latent image formed on the drum30 is developed into a visible image consisting of image dots formed ofa developing material in the form of a toner 50 (FIG. 14) deposited onthe drum 30 by a developing device 48 which will be described. Thevisible image is transferred from the photosensitive drum 30 onto thesheet 18 by the transfer device 32. The toner remaining on the drum 30is removed by a cleaning device 51.

The transfer device 32 includes a transfer roll 52 for charging thesheet 18 to transfer the toner 50 from the drum 30 onto the sheet 18.After the toner 50 is transferred to the sheet 18, the sheet 18 isdischarged by a suitable device, and is then fed to an image fixingdevice 54 while being guided by a suitable guide. The image fixingdevice 54 has a heating roll 56 and a pinch roll 58, for fixing thetoner 50 on the sheet 18. The sheet 18 leaving the fixing device 54 isejected by a pair of ejector rolls 60, onto a paper outlet tray 62attached to the front side of the main body 10.

Adjacent to the developing device 48, there is provided a humiditysensor 64 whose output is applied to the control device 40.

In an upper front portion of the main body 10, there is disposed animage reading device 66 which receives original sheets one after anotherfrom an original table 68, which provides an intermediate recessedportion of the top surface of the main body 10. Each original sheetbears an original image to be reproduced on the corresponding sheet 18,and is fed by an original feeding device 70 (FIG. 17) from the table 68to the image reading device 66 upon generation of a reading startcommand. The original feeding device 70 includes suitable feed rolls.The original sheets placed on the table 68 are detected by an originalsensor 72.

The image reading device 66 includes a light source 74, an originalsupport plate 76, reflector mirrors 78, 80, a condenser lens 82, and aline image sensor 84. The image on the original sheet on the supportplate 76 is irradiated by a radiation generated by the light source 74,and the radiation reflected by the original sheet is reflected by themirrors 78, 80. The radiation is then incident upon the line imagesensor 84 through the condenser lens 82. The line image sensor 84 readssuccessive lines of the image on the original sheet one line at a time.The original support plate 76 has a glass pane or other transparentplanar member supported by an opaque member. The original sheet isirradiated through the transparent planar member. The size of thepicture elements of the image read by the line image sensor 84 is thesame as that of the picture elements 42 of the electrostatic latentimage on the photosensitive drum 30 described above, when the resolutionis set at the SUPER-FINE value. In the present facsimile system, theresolution of the image is variable in three steps, that is, may be setat a selected one of SUPER-FINE, FINE and STANDARD values. The operatingspeed of the original feeding device 70 is controlled according to theselected resolution value. The original sheet which has passed theoriginal support plate 76 is fed out onto an original outlet tray 88 byan original ejector roll 86.

The developing device 48, which is constructed as described in detail inJapanese Patent Application 6-19227, will be described by reference toFIGS. 3-13.

As shown in FIG. 3, the developing device 48 has a housing 100 which isdivided by partition walls 102, 104 into three chambers: a cartridgechamber 106; an agitating chamber 108; and a developing chamber 110. Afirst and a second agitating member 112, 114 are disposed rotatably inthe agitating and developing chambers 108, 110, respectively.

The partition wall 102 which separates the cartridge and agitatingchambers 106, 108 from each other has an opening 116. Similarly, thepartition wall 104 which separates the agitating and developing chambers108, 110 from each other has an opening 118.

When a toner supply in the form of a toner cartridge 120 is received inthe cartridge chamber 106 as shown in FIG. 4, the toner 50 contained inthe toner cartridge 120 is supplied into the agitating chamber 108through the opening 116 while the toner 50 is agitated by a thirdagitating member 122, as indicated in FIG. 5. The toner 50 is thensupplied into the developing chamber 110 through the opening 118 whilethe toner is agitated by the first agitating member 112. The toner 50 inthe developing chamber 110 is agitated by the second agitating member114, together with a magnetic carrier accommodated in the developingchamber 110, whereby the toner 50 is fed up toward a developing sleeve124.

A restrictor plate 126 is disposed above the opening 118, to prevent amovement of the toner 50 from the agitating chamber 108 directly ontothe developing sleeve 124. Namely, the restrictor plate 126 functions todirect the toner 50 to the second agitating member 114 located below thedeveloping sleeve 124.

A major portion of the partition wall 102 has a cross sectional shape ofan arc having a center at a point within the cartridge chamber 106, asis apparent from FIG. 3. This arcuate portion of the partition wall 182follows the corresponding portion of the outer circumferential surfaceof the toner cartridge 120.

Within the developing sleeve 124, there is disposed a magnet roll 128.The developing sleeve 124 and the magnet roll 128 are rotated in theopposite directions. The toner 50 with the magnetic carrier is depositedon the circumferential surface of the developing sleeve 124, and thethickness of the layer of the toner 50 on the sleeve 124 is suitablyadjusted or controlled by a doctor blade 130 disposed adjacent to thesleeve 124.

The toner 50 uniformly deposited on the surface of the developing sleeve124 is charged by a charger 131, and is imagewise transferred to thelocal spots on the photosensitive drum 30 whose surface has beenimagewise exposed to the modulated laser beams. That is, the toner 50 istransferred from the sleeve 124 to the local spots 42 which have beenirradiated by the laser beams, but is not transferred to the local spots42 which have not been irradiated. Thus, the electrostatic latent imageformed by the scanner unit 34 is developed into the visible image of thetoner 50.

As indicated in FIG. 5, the cartridge chamber 106 is partially definedby opposite side walls 132 each of which has a U-shaped groove 134having a width H1, as indicated in FIG. 7. The U-shaped groove 134 hasan arcuate bottom portion 138. An engaging groove 136 is formed incommunication with the U-shaped groove 134 such that the engaging groove136 has an arcuate shape whose center is located at the center of thearcuate bottom portion 138 of the U-shaped groove 134. As indicated inFIG. 5, an engaging protrusion 141 having a shaft portion 139 and a headportion 140 is provided near the arcuate bottom portion 138. The headportion 140 has a larger diameter than the shaft portion 139. Theengaging protrusion 141 has parallel opposite flat faces, as shown inFIG. 7. A distance H2 between the flat faces of the protrusion 141 isslightly smaller than the width H1 of the U-shaped groove 134. As shownin FIG. 3, the bottom wall of the cartridge chamber 106 has athrough-hole 146 through which a sensing portion 144 of a residual toneramount sensor 142 (which will be described by reference to FIG. 14)extends.

To the inner surfaces of the opposite side walls 132 of the cartridgechamber 106, there are pivotally attached a pair of arms 150, as shownin FIG. 5. As shown in FIG. 8, each arm 150 has a support groove 154corresponding to the U-shaped groove 134 with the width H1, and anengaging recess 156 engageable with the engaging protrusion 141. Sincethe distance H2 of the engaging protrusion 141 is slightly smaller thanthe width H1, the engaging recess 156 can engage the engaging protrusion141 by moving the arm 150 in direction W (FIG. 7) such that an opening157 of the recess 156 leads in the movement direction W. The engagingprotrusion 141 and the engaging recess 156 are brought to an operatingposition by pivoting the arm 150 relative to the corresponding side wall132 after the engaging protrusion 141 has reached the bottom of therecess 156. In the operating position, the protrusion 141 and recess 156are not disengageable from each other and not rotatable relative to eachother.

In the operating position indicated above, the support groove 154 of thearm 150 is aligned with the U-shaped groove 134 of the side wall 132,and a relay portion 158 of the arm 150 substantially extends across theengaging groove 136, as shown in FIG. 4.

Each of the arms 150 has a pin 160 fixed thereto. The pin 160 extendsthrough an arcuate hole 162 formed through the corresponding side wall132, so that the pivotal movement of the art 150 is limited by abuttingcontact of the pin 160 with the ends of the arcuate hole 160, asindicated in FIG. 9.

A first shutter 164 is secured at its end portions to the arms 150, sothat the first shutter 164 closes the opening 116 formed through thepartition wall 102. The first shutter 164 is an arcuate plate having ashape following the arcuate shape of the partition wall 102. The firstshutter 164 is moved with the arms 150 upon pivotal movement of the arms150.

The first shutter 164 is locked at a position for closing the opening116 of the partition wall 102, by a first locking device 166, which willbe described.

The toner cartridge 120 is removably received in the cartridge chamber106 of the main body 10.

As shown in FIG. 6, the toner cartridge 120 has a housing 170, a pair oflevers 172 and a second shutter 174. The housing 170 has apart-cylindrical portion having a length in the axial direction of thedrum 30. The part-cylindrical portion has an opening 176 extending inthe longitudinal direction. The opening 176 is closed by a secondshutter 174. The part-cylindrical portion of the housing 170 has a pairof bottom projections 178 made of a transparent material, which arespaced apart from each other in the longitudinal direction, as shown inFIGS. 14 and 15. These bottom projections 178 define correspondingrecesses which are open in the bottom surface of the housing 170. Whenthe toner cartridge 120 is received in the cartridge chamber 106, theend portions of sensing portion 144 of the residual toner amount sensor142 are positioned within the recesses provided by the projections 178,as shown in FIG. 15.

The housing 170 has a pair of support shafts 179 extending throughrespective opposite end walls in the longitudinal direction. The supportshafts 179 are rotatable relative to the end walls of the housing 170.Each of these support shafts 179 supports a lever 172 such that thelever 172 is pivotable about the shaft 179. The lever 172 has a supportportion 180 and a handle portion 181. The second shutter 174 indicatedabove are attached to the support portions 180 of the two levers 172pivotally mounted on the respective shafts 179.

The second shutter 174 has two fixing end portions 182 attached to thesupport portions 180 of the levers 172. Each fixing end portion 182 hasa generally sectorial shape, and a U-shaped cutout 184 at its distalend, and an engaging hole 186 at a middle part thereof. The secondshutter 174 has a shutter portion extending between the fixing endportions 182. The shutter portion has an arcuate shape in cross section,which follows the part-cylindrical portion of the housing 170.

The support portion 180 of each lever 172 has substantially the sameshape as the fixing end portion 182 of the second shutter 174. Thesupport portion 180 has two guides 188 formed along the opposite edgesextending in the direction of its length. Each guide 185 has a detentpawl 187. The support portion 180 further has an engaging pawl 190,which is provided between the two guides 180, for engagement with theengaging hole 186 of the second shutter 174. The engaging pawl 190 has aright-triangular shape in cross section. The handle portion 181 has anengaging projection 192 formed at a proximal portion thereof, forengagement with the engaging groove 136 formed in the side wall 132. Thetwo levers 172 are connected to each other by a connecting rod 194, atthe distal ends of the handle portions 181, so that the two levers 172are pivoted as a unit. Each lever 172 has a support hole 195 forengagement with the support shaft 179 of the housing 170.

The second shutter 174 is attached to the support portions 180 of thelevers 172 such that the fixing end portions 182 engage the respectiveguides 188 and detent pawls 187 while the engaging pawls 190 engage theengaging hole 186, and such that the bottom portion of the cutout 184 ofthe second shutter 174 is aligned with the support hole 195. Thus, thesecond shutter 174 is moved with the levers 172 upon pivotal movement ofthe levers 172.

The assembly of the two levers 172 and the second shutter 174 isattached to the housing 170 such that the two support shafts 179 extendthrough the support holes 195 formed through the levers 172 and throughthe cutouts 184 formed through the fixing end portions 182 of the secondshutter 174. Thus, the toner cartridge 120 removably received in thecartridge chamber 106 is prepared.

The second shutter 174 is locked at a position for closing the opening176 of the housing 170, by a second locking device 196 which willdescribed.

Within the toner cartridge 170, the third agitating member 122 isdisposed rotatably about and with the support shafts 179, as shown inFIG. 5. The support shafts 179 are rotated by an agitating motor 200(FIG. 17), which is connected to the control device 40 through a motordriver 201, so that the third agitating member 122 is rotated with thesupport shafts 179 under the control of the control device 40. In thepresent facsimile system, the agitating motor 201 is activated tooperate the third agitating member 122 upon commencement of recording onthe sheet or sheets 18. Similarly, the first and second agitatingmembers 112, 114 are operated.

The third agitating member 122 includes a toner agitating portion 202located near the inner surface of the housing 170. The toner agitatingportion 202 has a central U-shaped portion 203, which functions toprevent an interference between the toner agitating portion 202 and thetransparent bottom projections 178 of the housing 170, during rotationof the third agitating member 122. Namely, the two bottom projections178 are located within the U-shaped portion 203 when the U-shapedportion 203 passes the bottom of the housing 170. The inner end of theU-shaped portion 203 remote from the inner surface of the housing 170 isaligned with the axis of rotation of the support shafts 179, that is,aligned with the axis of rotation of the agitating member 122. To theinner end of the U-shaped portion 203, there is attached an agitatingarm 204 which has a wiper 206 at its distal end. The wiper 206 is formedof a felt or other fibrous material, or consists of a sponge or othersoft porous member. The wiper 206 is adapted to pass a space between thetwo bottom projections 178, to remove a mass of the toner 50 in thatspace and clean the opposite surfaces of the projections 178 each timethe agitating member 122 is rotated.

As shown in FIGS. 11 and 12, the second locking device 196 includes asheet spring 220 fixed to the housing 170, and has an engaging hole 222formed in the second shutter 174. The sheet spring 220 has a bentengaging portion 224 which is engageable with the engaging hole 222 ofthe second shutter 174, for locking the second shutter 174 relative tothe housing 170, at the position for closing the opening 176.

The second shutter 174 has a U-shaped cutout 226 located within the areaof the sheet spring 220 when the second shutter 174 is in the lockedposition. The cutout 226 is provided for unlocking the second shutter174. The housing 170 has a sealing member in the form of a felt 230disposed along the periphery of the opening 176, as shown in FIG. 6. Thefelt 230 prevents leakage of the toner 50 through a gap between thehousing 170 and the second shutter 174.

As shown in FIG. 12, the partition wall 102 of the housing 100 of thedeveloping device 48 has a tab 232 located above the opening 116. Thetab 232 is engageable with the cutout 226 when the toner cartridge 120is received in place in the cartridge chamber 106. Described morespecifically, when the toner cartridge 120 is positioned within thecartridge chamber 106, the tab 232 pushes the sheet spring 220 towardthe housing 170, extending through the cutout 226, whereby the engagingprojection 224 is disengaged from the engaging hole 222, and the secondshutter 174 is unlocked. As a result, the assembly of the second shutter174 and levers 172 can be pivoted about the support shafts 179.

The first locking device 166 has a locking arrangement similar to thatof the second locking device 196. As shown in FIG. 13, the first lockingdevice 166 includes a sheet spring 240 fixed to a portion of thepartition wall 102 above the opening 116. The sheet spring 240 has abent engaging projection 242, while the first shutter 164 has anengaging portion 244 formed near the upper edge. The engaging projection242 is engageable with the engaging portion 244, for locking the firstshutter 164 at the position for closing the opening 116. The partitionwall 102 has a sealing member in the form of a felt 246 disposed alongthe periphery of the opening 116.

The housing 170 of the toner cartridge 120 has a tab 250 located abovethe opening 176. The tab 250 is provided to push the sheet spring 240 tounlock the first shutter 164 and permit pivotal movement of the firstshutter 164 and the arms 150 relative to the partition wall 102.

When the toner cartridge 120 is positioned in the cartridge chamber 106,the support shafts 179 are inserted into the U-shaped grooves 134 andsupport grooves 154, in the direction indicated at E in FIG. 4. In thiscondition, the housing 170 of the toner cartridge 120 is positionedclose to the partition wall 102, so that the tab 250 pushes the sheetspring 240 of the first locking device 166, while the tab 232 pushes thesheet spring 220 of the second locking device 196, whereby the first andsecond shutters 164, 174 are unlocked from the first and second lockingdevices 166, 196.

Then, the levers 172 are operated at the handle portions 181, so as tobe pivoted in the direction indicated at F in FIG. 9, so that the secondshutter 174 is pivoted relative to the housing 170, to open the opening176, while at the same time the engaging projections 192 on the levers172 act on the relay portions 158 of the levers 150, so as to pivot thelevers 150 and the first shutter 164 relative to the partition wall 102,whereby the opening 116 is opened.

Since the arms 150 are pivoted relative to the housing 100 (side walls132), the grooves 154 and the grooves 134 intersect each other, and theopen ends of these grooves 154, 134 are closed. Further, the engagementof the engaging projections 192 with the engaging grooves 136 preventsdisengagement of the support shafts 179 of the toner cartridge 120 fromthe U-shaped grooves 134.

There will next be described the residual toner amount sensor 142.

The sensor 142 is constituted by the sensing portion 144 and the wiper206 attached to the third agitator 122, as shown in FIGS. 14 and 15. Thesensing portion 144 is secured to a lower support plate 256 of thefacsimile system. The sensor 142 is of a light-transmitting photosensortype wherein the sensing portion 144 has a light emitting element and alight sensitive element.

The sensing portion 144 extends through the through-hole 146 formedthrough the bottom wall of the housing 100 of the developing device 48.The light emitting element of the sensing portion 144 is located withinone of the two U-shaped recesses formed by the respective bottomprojections 178 of the housing 170 of the toner cartridge 120, while thelight sensitive element is located within the other U-shaped recess, asindicated in FIG. 14. As described above, the bottom projections 178 areformed of a transparent material, so that a light beam generated by thelight emitting element of the sensing portion 144 is received by thelight sensitive element when the space between the two projections 178is not filled with the toner 50, or when only a small amount of thetoner 50 is present in that space.

If the level of the upper surface of the mass of toner 50 is higher thanthe light emitting and sensitive elements of the sensing portion 144 andif the wiper 206 is not located within the space between the bottomprojections 178, the light beam generated by the light emitting elementis blocked by the toner 50 filling the above-indicated space. In thiscase, therefore, no light is received by the light sensitive element.

In operation of the facsimile system, the third agitating member 122 isrotated, and the wiper 206 passes the above-indicated space each timethe agitating member 122 is rotated. The passage of the wiper 206 causesthe toner 50 to be removed from the above-indicated space, and alsocauses the opposite surfaces of the projections 178 to be cleaned by thewiper 206. Consequently, the light beam is temporarily received by thelight sensitive element even if the amount of the toner 50 issufficiently large. However, immediately after the wiper 206 has passedthe above-indicated space, the space is re-filled by the toner 50, andthe emitted light beam is blocked by the toner until the wiper 206 againenters the above-indicated space. Thus, the time period during which thelight beam is received by the light sensitive element is shorter thanthe time period during which the light beam is blocked.

If the amount of the toner 50 is relatively small but theabove-indicated space is filled with the toner 50, the time required forthe toner 50 to re-fill the space after the toner in the space isremoved by the wiper 206 is relatively long, whereby the time periodduring which the light beam is received by the light sensitive elementis relatively long.

Therefore, the amount of the toner 50 remaining in the toner cartridge50 can be detected on the basis of the time period during which thelight beam generated by the light emitting element of the sensingportion 144 is received by the light sensitive element, namely, on thebasis of a period between a moment at which the light sensitive elementis turned ON and a moment at which the light sensitive element is turnedOFF.

The output of the residual toner amount sensor 142, more precisely, theoutput of the light sensitive element of the sensing portion 144 isapplied to the control device 40, which determines whether the periodduring which the light sensitive element is held ON is longer than apredetermined threshold. If the period is longer than the threshold,this means that the residual amount of the toner 50 is not sufficientlylarge, and that the cartridge 120 should be replaced with a new one in ashort time. In this case, a CONDITION flag 1 used by the control device40 is set to "1", as described below.

As the third agitating member 122 is operated during a recordingoperation of the facsimile system, the output of the sensor 142 isapplied to the control device 40 during the recording operation.

Referring next to FIG. 19, there will be described the operator'scontrol panel 14 provided on the upper surface of the front portion ofthe main body 10 of the facsimile system.

The operator's panel 14 has a relative rear section which provides adisplay 300 and a TONER SAVE light 302, a relatively front section whichprovides TEN keys 304, a SPEED DIAL key 306, a START key 308, a STOP key310, and a COPY key 312, and an intermediate section which provides aFUNCTION key 314, a SET key 316, a CLEAR key 318, a RESOLUTION key 320,and CURSOR keys 322, 324.

The display 300 is adapted to indicate operating conditions of thefacsimile system, and provides the user with procedures for operatingthe facsimile system. The TONER SAGE light 302 is turned on when theuser has selected a TONER-SAVE recording mode or when a TONER SAVE flag(which will be described) is set at "1".

The TEN keys 304 are used to enter the facsimile or telephone numbers ofremote facsimile systems (remote facsimile receivers) 325 (FIG. 17) whenfacsimile data are sent to the remote facsimile receivers 325. The TENkeys 304 are also used to register the facsimile numbers of the desiredremote facsimile systems 325 in relation to respective facsimile numbercodes (e.g., two- or three-digit codes), and to select various functionsof the present facsimile system.

The SPEED DIAL key 306 is used to generate the remote facsimile numberrepresented by the facsimile number code entered through the TEN keys304. The START key 308 is used to start the transmission of facsimiledata to the specified remote facsimile receiver 325, and to register thepatterns of call signals which call two or more telephone numbers usedby the present facsimile system, which is of a distinctive ringing typeas disclosed in co-pending U.S. application Ser. No. 08/348,900. TheSTOP key 310 is used to stop the selected functions, for example.

The FUNCTION key 314 is also used to provide indications on the display300 of the functions available in the present facsimile system. The SETkey 316 is used to set entered data for the various functions, while theCLEAR key 318 is used to cancel the selected functions. The RESOLUTIONkey 320 is used to select the resolution of the image to be reproduced.The image resolution is normally set at the STANDARD value. When theRESOLUTION key 320 is pressed once, the resolution is set to the FINEvalue. When the key 320 is pressed twice, the resolution is set to theSUPER-FINE value. When the key 320 is pressed three consecutive times,the facsimile system is placed in a GRAY SCALE mode in which the densityof the image to be reproduced is set by the FUNCTION and CURSOR keys314, 322, 324.

The CURSOR keys 322, 324 are used to move a cursor on the screen on thedisplay 300, and to select the various functions. The CURSOR keys 322,324 are also used to correct erroneously entered data, for example,erroneously entered numbers when the remote facsimile numbers areregistered in relation to the respective facsimile number codes.

As shown in FIG. 2, the control device 40 is disposed in a lower sectionof the facsimile system. As indicated in the block diagram of FIG. 17,the control device 40 incorporates a central processing unit (CPU) 330,a random-access memory (RAM) 332, a read-only memory (ROM) 334, anelectrically erasable programmable read-only memory (EEPROM) 336, adigitizing circuit 338, a threshold circuit 340, a parallel/serialconverter circuit 342, an encoder/decoder circuit 344 and atransmission/reception control circuit 346. To the control device 40,there are connected the image reading device 66, the operator's controlpanel, the residual toner amount sensor 142, the paper sensor 25, theoriginal sensor 72 and the humidity sensor 64. The control device 40 isconnected to a telephone line 359 through a MODEM 350 and a networkcontrol unit (NCU) 352, so that the control unit 40 communicates with aselected one of the remote facsimile systems 325 through the telephoneline 359. The control device 40 controls the agitating motor 200 for thethird agitating member 122, the original feeding device 70 and a ringingdevice 358 through the respective drivers 201, 354, 356.

The digitizing circuit 338 converts analog image data from the imagereading device 66 into binary image data, using a threshold value givenby the threshold circuit 340. The parallel/serial converter circuit 342functions to parallel signals into serial signals or vice versa. Theencoder/decoder circuit 344 functions to convert received coded imagedata into decoded image data in the form of dot data, and to convert thedot data into coded image data when the image data in the form of thedot data are transmitted to the remote facsimile system (remotefacsimile receiver) 325. The transmission/reception control circuit 346is used to effect the transmission and reception of ancillary data ofthe facsimile data, between the present facsimile system and the remotefacsimile system 325, through the telephone line 359. The ancillary datainclude data indicative of the image resolution, and data indicative ofthe facsimile or telephone numbers of the present facsimile system andthe remote facsimile system 325.

The MODEM 350 functions to modulate digital signals into analog signals,so that the analog signals are sent to the remote facsimile system 325through the telephone line 359 and the NCU 352, and to demodulate analogsignals from the remote facsimile system 325 into digital signals. TheNCU 352 automatically receives the analog signals upon reception of acall signal from the remote facsimile system 325 through the telephoneline 359, and automatically generates a call signal calling the remotefacsimile system 325 upon data transmission to the remote facsimilesystem.

The ringing device 358 is activated by the driver 356 to generate aringing sound, in response to the call signal received from the remotefacsimile system 325 (through a telephone company), or in response to acommand from the control device 40. The driver circuit 356 applies avoltage signal to the ringing device 358 depending upon the pattern ofthe received call signal.

The voltage applied to the ringing device 358 through the driver 356changes in two steps. The device 358 as energized to produce a soundwhen the voltage is low, and is de-energized when the voltage is high.Each call signal has ON and OFF states (ON and OFF times) correspondingto the low and high levels of the voltage applied to the ringing device358. Different call signals have different patterns which are defined bythe numbers and time lengths of the ON and OFF states. In each pattern,the number of the ON state or states in each period of the call signalis equal to the number of the OFF state or states, and one long OFFstate is included in each period of the call signal so that each periodcan be determined by detecting the long OFF state. The present facsimilesystem of distinctive ringing type uses different telephone or facsimilenumbers which are called by the respective call signals having differentpatterns.

As shown in FIG. 20, the RAM 332 includes: an ENCODE RECEPTION IMAGEDATA memory 360 for storing coded image data received from the remotefacsimile system 325; a DECODED RECEPTION IMAGE DATA memory 362 forstoring decoded image data (i.e., dot data) obtained from the encodedimage data; a TRANSMISSION IMAGE DATA memory 364 for storing image dataobtained by the image reading device 66; a CALL NUMBER DATA memory 366for storing number-related data indicative of the distinctive ringingtelephone number of the present facsimile system which has been actuallycalled by the call signal received from the remote facsimile transmitter325; a REMOTE FACSIMILE TRANSMITTER NUMBER DATA memory 368 for storingnumber-related data indicative of the facsimile number of the remotefacsimile transmitter 325 from which image data have been received; aREMOTE FACSIMILE RECEIVER NUMBER DATA memory 370 for storing dataassociated with the facsimile numbers of the selected remote facsimilereceivers 325; and a COMMUNICATION RECORD DATA memory 372 for storingfacsimile communication report data representative of a communicationreport which indicates facsimile communications with the remotefacsimile systems 325.

As shown in FIG. 21, the ROM 334 includes: a RECORDING CONTROL programmemory 380; an IMPORTANT IMAGE DATA FLAG 1 SETTING program memory 381;an IMPORTANT IMAGE DATA FLAG 2 SETTING program memory 382; a REMOTERECEIVER DATA SETTING program memory 383; a COMMUNICATION RECORDIMPORTANCE SETTING program memory 384; a TONER SAVE FLAG SETTING programmemory 385; an OPERATING CONDITION FLAG SETTING program memory 386; aRESIDUAL TONER AMOUNT SENSING program memory 387; a GRAY SCALE FLAGSETTING program memory 388; a RELATION TABLE memory 389; a TONER SAVEMARKING DATA GENERATION program memory 390; and a COMMUNICATION RECORDOUTPUT program memory 391. The programs stored in these program memories380-391 will be described below.

The EEPROM 336 includes a CALL SIGNAL PATTERN memory 392 and a CONDITIONflag 1. The CALL SIGNAL PATTERN memory 392 stores data indicative of thedifferent patterns of the call signals assigned to call selected ones ofthe distinctive ringing telephone numbers of the present facsimilesystem. The OPERATING CONDITION flag 1 is set to "1" when the controldevice 40 determines, on the basis of the output of the residual toneramount sensor 142, that the amount of the toner 50 remaining in thetoner cartridge 120 is smaller than a predetermined limit.

There will be described an operation of the present facsimile system.

The facsimile system operates to effect recording on the paper sheet orsheets 18 according to image data generated on the basis of facsimiledata received from the remote facsimile transmitter 325, under thecontrol of the control device 40. When the TONER SAVE flag is set at"0", the control device 40 is placed in the NON-TONER-SAVE recordingmode in which the scanner unit 34 is operated according to the originalimage data (non-toner-save image data). When the TONER SAVE flag is setat "1", the control device 40 is placed in a TONER-SAVE recording modein which the scanner unit 34 is operated according to toner-save imagedata. The toner-save image data are generated on the basis of theoriginal image data as received from the remote facsimile transmitter325.

While the TONER SAVE flag may be manually set by the user of the presentfacsimile system, this flag is automatically set by the control device40 in the present embodiment, as described below, in a TONER SAVE FLAGSETTING routine according to a program stored in the program memory 385,as illustrated in the flow chart of FIG. 23.

The TONER SAVE FLAG SETTING routine is initiated with step S1 todetermine whether an IMPORTANT IMAGE DATA flag 3 is set at "1". If anegative decision (NO) is obtained in step S1, the control flow goes tostep S2 to determine whether a GRAY SCALE flat is set at "1". If anegative decision (NO) is obtained in step S2, the control flow goes tostep S3 to determine whether any one of other flags such as an OPERATINGCONDITION flag and a USER-SET flag is set at "1". If an affirmativedecision (YES) is obtained in any one of steps S1-S3, that is, if anyone of the IMPORTANT IMAGE DATA flag 3, GRAY SCALE flag and the otherflags is set at "1", the control flow goes to step S4 to reset the TONERSAVE flag to "0". If the negative decision (NO) is obtained in all thesteps S1-S3, the control flow goes to step S5 to set the TONER SAVE flagto "1".

The IMPORTANT IMAGE DATA flag 3 is set to "1" when the subject matter orcontent of primary data or image data of the facsimile data receivedfrom the remote facsimile transmitter 325 is considered to be importantto the user of the present facsimile system. The IMPORTANT IMAGE DATAflag 3 is set or reset according to the states of an IMPORTANT IMAGEDATA flag 1 and an IMPORTANT IMAGE DATA flag 2. More specifically, theIMPORTANT IMAGE DATA flag 3 is set to "1" when either one of theIMPORTANT IMAGE DATA flags 1 and 2 is set at "1", and is reset to "0"when both of the IMPORTANT IMAGE DATA flags 1 and 2 are set at "0".

It is generally difficult to determine whether the subject matter orcontent of the received original image data is important or not, beforean image is recorded or reproduced according to the received originalimage data. The present embodiment is uniquely arranged to estimate thatthe subject matter of the received original image data is important, ifthe remote facsimile transmitter 325 from which the image data have beenreceived is one of predetermined remote facsimile transmitters orfacsimile systems (remote parties) which are expected to transmit imagedata whose importance is relatively high.

To determine whether the remote facsimile transmitter 325 is one of thepredetermined remote parties, an IMPORTANT IMAGE DATA FLAG 1 SETTINGroutine and an IMPORTANT IMAGE DATA FLAG 2 SETTING routine are executedaccording to the programs stored in the program memories 381 and 382, asillustrated in the flow charts of FIGS. 24 and 25, respectively. Theroutine of FIG. 24 for setting or resetting the IMPORTANT IMAGE DATAflag 1 is executed on the basis of the data stored in the CALL NUMBERDATA memory 366 and the data stored in the CALL SIGNAL PATTERN memory392, while the routine of FIG. 25 for setting or resetting the IMPORTANTIMAGE DATA flag 2 is executed on the basis of the data stored in theREMOTE FACSIMILE TRANSMITTER NUMBER DATA memory 368 and the data storedin the REMOTE FACSIMILE RECEIVER NUMBER DATA memory 370. The data storedin the memories 366, 368 are received from the remote transmitter 325,as part of the facsimile data other than the primary data (image data),namely, as ancillary data associated with facsimile communicationsbetween the present facsimile system and the remote facsimile system.

The IMPORTANT IMAGE DATA flag 1 is a flag controlled on the basis of thedata indicative of the facsimile number of the present or receivingfacsimile system which is designated by the call signal received fromthe remote facsimile transmitter 325 (through a telephone company). Asdescribed above, the present facsimile system of the distinctive ringingtype uses different telephone or facsimile numbers which are called byrespective call signals of different patterns. When these different callsignals are received, the ringing device 358 generate ringing sounds ofthe corresponding different patterns, under to a distinctive ringingservice available from the telephone company. Usually, only theimportant remote calling parties (users of the remote facsimiletransmitters 325) have been informed of the different facsimile numbers.Therefore, the remote facsimile transmitter 325 from which the callsignal calling one of the different facsimile numbers of the presentfacsimile system has been received is considered to be one of thepredetermined remote facsimile transmitters 325 which are expected totransmit image data whose subject matter or content is relativelyimportant to the user of the present facsimile system.

To utilize the distinctive ringing service, the patterns of the callsignals corresponding to selected ones of the different facsimilenumbers used by the present facsimile system (facsimile receiver) arestored in the CALL SIGNAL PATTERN memory 392 of the EEPROM 336. Thepatterns (combinations of time lengths of ON and OFF states) of thecorresponding call signals are registered in a predetermined procedureby manipulation of the operator's control panel 14. When a call signalhas been received from a certain remote facsimile transmitter 325, thefacsimile number designated by the call signal and the correspondingpattern are stored in the CALL NUMBER DATA memory 366. This pattern ofthe received call signal stored in the memory 366 is compared with thepatterns of the call signals stored in the CALL SIGNAL PATTERN memory392, to determine whether the pattern of the received call signal isregistered in the memory 392, according to the IMPORTANT IMAGE DATA FLAG1 SETTING routine of FIG. 24.

The IMPORTANT IMAGE DATA FLAG 1 SETTING routine is initiated with stepS11 in which the pattern of the received call signal is stored in thememory 366. Step S11 is followed by step S12 to determine whether thepattern stored in the memory 366 is identical with any one of thepatterns stored in the memory 392. If an affirmative decision (YES) isobtained in step S12, step S13 is implemented to activate the ringingdevice 358 to generate a distinctive ringing sound corresponding to theregistered pattern of the received call signal. If a negative decision(NO) is obtained in step S12, the control flow goes to step S14 toactive the ringing device 358 to generate a predetermined normal ringingsound (according to a pattern not registered in the memory 392).

Steps S13 and S14 are followed by step S15 identical with step S12. Ifan affirmative decision (YES) is obtained in step S15, the control flowgoes to step S16 to set the IMPORTANT IMAGE DATA flag 1 to "1". If anegative decision (NO) is obtained in step S15, the control flow goes tostep S17 to reset the IMPORTANT IMAGE DATA flag 1 to "0". Thus, theIMPORTANT IMAGE DATA flag 1 is set to "1" when the received call signaldesignates one of the facsimile numbers of the distinctive ringingservice, namely, when the subject matter of the received original imagedata is important.

The IMPORTANT IMAGE DATA flag 2 is a flag controlled on the basis of thedata indicative of the facsimile number of the remote facsimiletransmitter 325 from which facsimile data have been received. In thepresent facsimile system, the facsimile numbers of the selected remotefacsimile receivers 325 are stored in the REMOTE FACSIMILE RECEIVERNUMBER DATA memory 370, in relation to the corresponding facsimilenumber codes (e.g., two- or three-digit codes), which are entered,rather than the facsimile numbers per se, by the SPEED DIAL and TEN keys306, 304 on the operator's control panel to designate the desired remotefacsimile receiver 325. The use of these facsimile number codesfacilitate the facsimile transmission procedure. If the facsimile numberof the remote facsimile transmitter 325 from which the image data havebeen received is one of the facsimile numbers of the remote facsimilereceivers 325 stored in the memory 370, the IMPORTANT IMAGE DATA flag 2is set to "1". Usually, the facsimile number codes are assigned to thepredetermined remote facsimile systems 352 which are expected totransmit image data whose subject matter or content is important to theuser of the present facsimile system.

The facsimile numbers and the corresponding codes of the predeterminedremote facsimile systems (receivers) 325 are registered in the REMOTEFACSIMILE RECEIVER NUMBER DATA memory 370 through the operator's controlpanel 14. When image data have been received from a given remotefacsimile transmitter 325, the facsimile number of that remote facsimiletransmitter is stored in the REMOTE FACSIMILE TRANSMITTER NUMBER DATAmemory 368, and is compared with the facsimile numbers stored in theREMOTE FACSIMILE RECEIVER NUMBER DATA memory 370, to determine whetherthe facsimile number stored in the memory 368 is identical with one ofthe facsimile numbers stored in the memory 370. To this end, theIMPORTANT IMAGE DATA FLAG 2 SETTING routine is executed as illustratedin the flow chart of FIG. 25.

The IMPORTANT IMAGE DATA FLAG 2 SETTING routine of FIG. 25 is initiatedwith step S21 in which the facsimile number of the remote facsimiletransmitter 325 is stored in the memory 368. Step S21 is followed bystep S22 to determine whether the facsimile number in the memory 368 isidentical with any one of the facsimile numbers registered in the memory370. If an affirmative decision (YES) is obtained in step S22, thecontrol flow goes to step S23 to set the IMPORTANT IMAGE DATA flag 2 to"1". If a negative decision (NO) is obtained in step S22, the controlflow goes to step S24 to reset the IMPORTANT IMAGE DATA flag 2 to "0".

The GRAY SCALE DATA flag is set to "1" when the received image data aregray scale data. If image recording is effected in the TONER-SAVErecording mode according to the gray scale image data, there may arise aproblem relating to the uniformity and gradation of the image density.

The gray scale image data are formulated to form an image in a dithermatrix, namely, to represent a gray scale image by only one of twolevels "white" and "black" corresponding to dot data bits "0" and "1".Accordingly, the logical values of the adjacent dot data bits obtainedfrom the gray scale data tend to change relatively frequently. In otherwords, a unit volume of the dot data obtained by conversion from thegray scale data have comparatively large number of pairs of adjacentbits which have different logical values "0" and "1". Therefore, adetermination as to whether the received image data are gray scale datacan be effected by checking if the number of such pairs of adjacent bitsper unit volume of the dot data obtained from the received image data islarger than a predetermined threshold value. Alternatively, thedetermination may be made on the basis of compressed run length codes.

In the present embodiment, the determination is effected on the basis ofan initial portion of a batch of dot data as indicated in FIG. 30, whichis obtained by decoding encoded image data (as indicated in FIG. 29)received from the remote facsimile transmitter 325. If all of the dotdata sets for the first, second and third lines of the image aredetermined to be gray scale data, the dot data batch is determined to begray scale data. This method of determination assures reliable settingof the GRAY SCALE flag.

The GRAY SCALE flag is set or reset by a GRAY SCALE DATA FLAG SETTINGroutine according to a program stored in the GRAY SCALE DATA FLAGSETTING program memory 388, as illustrated in the flow chart of FIG. 26.

The GRAY SCALE DATA FLAG SETTING routine of FIG. 26 is initiated withstep S31 in which line number "L" and count "C" are initialized to "0".Step S31 is followed by step S32 to calculate the number "Ns" of thepairs of adjacent dot data bits having different logical states, whichpairs are included in the dot data set for the first line of image.Then, the control flow goes to step S33 to determine whether the number"Ns" is larger than a predetermined threshold. If an affirmativedecision (YES) is obtained in step S33, the control flow goes to stepS34 to increment the count "C". If a negative decision (NO) is obtainedin step S33, step S35 is implemented to maintain the present count "C".Steps S34 and S35 are followed by step S36 to determine whether the linenumber "L" is equal to or larger than a predetermined value "s". In thisspecific example, the value "s" is equal to "3", as indicated above. Anegative decision (NO) is obtained in step S36 in the first cycle ofexecution of the routine (in which the line number "L" is equal to "1").In this case, step S37 is implemented to increment the line number "L",and the control flow goes back to step S32 and repeat the followingsteps S33-S37 until an affirmative decision (YES) is obtained in stepS36. When the step S33 has been implemented for the number "Ns" for thethird line of image, the affirmative decision (YES) is obtained in stepS36, and the control flow goes to step S38 to determine whether thecount "C" is equal to or larger than the predetermined value "3". If thenumber "Ns" is equal to "3", step S39 is implemented to set the GRAYSCALE DATA flag to "1". If the number "Ns" is equal to "0", "1" or "2",the control flow goes to step S40 to reset the GRAY SCALE DATA flag to"0".

The OPERATING CONDITION flag is set or reset by the OPERATING CONDITIONSETTING routine according to a program stored in the memory 386, asillustrated in the flow chart of FIG. 27, depending upon selectedoperating conditions of the present facsimile system, that is, thedetected amount of the toner 50 remaining in the toner cartridge 120,detected humidity within the facsimile system, and absence or presenceof the paper sheet 18 on the manual sheet insertion table 24.

The OPERATING CONDITION FLAG SETTING routine of FIG. 27 is initiatedwith step S51 to determine whether the CONDITION flag 1 stored in theEEPROM 336 is set at "1". If a negative decision (NO) is obtained instep S51, the control flow goes to step S52 to determine whether aCONDITION flag 2 is set at "1". If a negative decision (NO) is obtainedin step S52, step S53 is implemented to determine whether a CONDITIONflag 3 is set at "1". If an affirmative decision (YES) is obtained inany one of the steps S51-S53, the control flow goes to step S54 to resetthe OPERATING CONDITION flag to "0" to select the TONER-SAVE recordingmode (with the negative decision obtained in step S3), if the IMPORTANTIMAGE DATA flag 3 and the GRAY SCALE flag are both set at "0". If thenegative decision (NO) is obtained in all of the three steps S51-S53,the control flow goes to step S55 to set the OPERATING CONDITION flag to"1" to select the NON-TONER-SAVE recording mode (with the affirmativedecision obtained in step S3).

The CONDITION flag 1 is set to "1" if the amount of the toner 50remaining in the toner cartridge 120 is smaller than the predeterminedthreshold. In this case, the TONER-SAVE recording mode is selected toreduce the rate of consumption of the toner 50 and thereby defer thereplacement of the toner cartridge 120 with a new one.

The residual amount of the toner 50 is detected on the basis of theoutput signal of the residual toner amount sensor 142, by a RESIDUALTONER AMOUNT SENSING routine according to a program stored in theprogram memory 387, as illustrated in the flow chart of FIG. 28.

In the present embodiment, the output signal of the sensor 142 isdetected three times upon starting of a recording operation according toimage data. The CONDITION flag 1 is set to "1" if all of the threedetections indicate that the residual amount of the toner 50 is smallerthan the threshold value. Described more specifically, the routine ofFIG. 28 is initiated with step S61 to determine Whether the CONDITIONflag 1 is currently set at "1". If the amount of the toner 50 issufficiently large and the CONDITION flag 1 is currently set at "0", thecontrol flow goes to step S62 to determine whether the light receivingtime "t" of the light sensitive element of the sensing portion 144 ofthe sensor 142 is longer than a predetermined threshold "Tu". See FIG.16. If an affirmative decision (YES) is obtained in step S62 for all thethree detections of the output signals of the sensor 142, it means thatthe amount of the toner 50 is smaller than the predetermined value, andthe control goes to step S63 to set the CONDITION flag 1 to "1". In thiscase, the OPERATING CONDITION flag is reset to "0", and the negativedecision (NO) is obtained in step S3, whereby the TONER-SAVE flag is setto "1" to establish the TONER-SAVE recording mode if the negativedecision (NO) is obtained also in steps S1 and S2.

If the CONDITION flag is currently set at "1", the affirmative decision(YES) is obtained in step S61, and the control flow goes to step S64 todetermine whether the light receiving time "t" is shorter than apredetermined threshold "Td". If an affirmative decision (YES) isobtained in step S64 for all the three detections of the output signalsof the sensor 142, the control goes to step S65 to reset the CONDITIONflag 1 to "0", since the residual amount of the toner 50 is stillsufficient and the CONDITION flag 1 has been erroneously set at "1".

As indicated above, the two different threshold values "Tu" and "Td" areused to change the value of the CONDITION flag 1. Namely, the twothreshold values "Tu" and "Td" provide a control hysteresis to prevent"hunting", namely, frequent changes in the state of the CONDITION flag1.

If the light receiving time "t" is not smaller than the threshold value"Td", the CONDITION flag 1 is held at "1".

The CONDITION flag 2 is set or reset depending upon the humidity withinthe present facsimile system, as a parameter representative of anoperating environment of the facsimile system. More specificallydescribed, the CONDITION flag 2 is reset to "0" to select theNON-TONER-SAVE recording mode if the humidity detected by the humiditysensor 64 is higher than a predetermined threshold. When the humidity isrelatively high, the toner 50 tends to easily adhere to the surface ofthe photosensitive drum 30, and is less likely to be easily transferredto the paper sheets 18. If the developing device 48 is operated in theTONER-SAVE recording mode, the recorded image tends to be unclear.

The CONDITION flag 3 is set or reset depending upon the recording mediumon which the recording is effected. Described more specifically, theCONDITION flag 3 is set to "1" to select the TONER-SAVE recording modeif the paper sheet 18 placed on the manual sheet insertion table 24 isdetected by the sensor 25. Usually, the paper sheet 18 placed on themanual sheet insertion table 24 is a reclaimed paper sheet or apartially used sheet (one surface of which has a recorded image), whichsheets are not expected to be kept for a long time. That is, a recordingon such a paper sheet in the TONER-SAVE mode is generally acceptable.

The USER-SET flag which is also to be checked by step S3 of the TONERSAVE FLAG SETTING routine of FIG. 23 is set or reset manually by theuser of the present facsimile system.

To set or reset the USER-SET flag, the FUNCTION key 314 and a numeralkey "5" of the TEN keys 304 are pressed to provide a menu of functionson the display 300. Then, a numeral key "6" of the TEN keys 304 ispressed, whereby the display 300 provides an indication "6. TONER SAVE".Then, the SET key 316 is pressed, and the display 300 alternatelyprovides indications "TONER SAVE: OFF" and "SELECT<>& SET". Theindication "TONER SAVE: OFF" means that the NON-TONER-SAVE recordingmode is currently selected, while the indication "SELECT<>& SET" promptsthe user to select the TONER-SAVE or NON-TONER-SAVE recording mode bythe CURSOR key 322, 324 and press the SET key 316.

If the TONER-SAVE recording mode is selected by the CURSOR key 324according to the prompting indication, the display 300 provides anindication "TONER SAVE". If the NON-TONER-SAVE recording mode isselected by the CURSOR key 322, the display 300 provides an indication"TONER SAVE: OFF". In either of these cases, the SET key 316 should bepressed. Then, the display 300 provides the indication "6. TONER SAVE".

Thus, the user may set or reset the USER-SET flag to set or reset theTONER SAVE flag depending upon the degree of importance of originalimage data to be reproduced, or set the TONER SAVE flag if the userdesires to effect a recording in the TONER-SAVE mode for some reason orother. It will be understood that the FUNCTION key 314, CURSOR keys 322,324, SET key 316 and TEN keys 304 provide operator-controlled means forchanging the state of the TONER SAVE flag or for selecting theTONER-SAVE or NON-TONER-SAVE recording mode.

The TONER SAVE flag is automatically set to "1" also when the usercommands the control device 40 to produce a facsimile communicationrecord which includes some of the ancillary data indicated above, whichrepresent the facsimile numbers of the remote facsimile systems 325 toand from which facsimile data have been transmitted or received. Suchancillary data are stored in the COMMUNICATION RECORD DATA memory 372.The facsimile communication record is produced according to a programstored in the program memory 391. Since the degree of importance of thefacsimile communication record is considered to be comparatively low,the TONER SAVE flag is set to "1" to produce the record in theTONER-SAVE recording mode.

To command the control device 40 to produce the facsimile communicationrecord, the FUNCTION key 314 and a numeral key "3" of the TEN keys 304are first pressed. As a result, the display 300 provides an indication"1. COMMUNICATION RECORD". In this condition, the SET key 316 ispressed, and the TONER SAVE flag is set to "1". The display 300 thenprovides an indication "PRESS START key". When the START key 308 ispressed, an operation to produce the facsimile communication record isstarted. and the display 300 provides the indication "1. COMMUNICATIONRECORD".

As described above, the TONER SAVE flag is automatically set or resetdepending upon the importance or nature or type of the original image tobe reproduced, and depending upon the operating conditions orenvironment of the present facsimile system. A recording operation iseffected in the TONER-SAVE or NON-TONER-SAVE mode selected by the TONERSAVE flag, according to the original image data generated on the basisof the primary data of the facsimile data received from a remotefacsimile transmitter 325, or ancillary data of the facsimile datastored in the COMMUNICATION RECORD DATA memory 372. The original imagedata as received from the remote facsimile receiver 325 take the form ofencoded image data and are stored in the ENCODED RECEPTION IMAGE DATAmemory 360. The encoded image data are converted by the encoder/decodercircuit 344, into decoded image data in the form of dot data, and arestored in the DECODED RECEPTION IMAGE DATA memory 362.

The dot data consist of a multiplicity of dot data bits which indicatethe presence or absence of image dots at the respective local spots orpicture element positions 42 (FIG. 18) of a dot matrix. The position ofeach picture element 42 in the dot matrix is defined by line number andcolumn number of the matrix. The number of the picture elements 42 inone line of the dot matrix varies depending upon the size of the papersheet 18. Where the paper sheet 18 is the A4-size sheet, each line ofthe dot matrix consists of a total of 1728 picture elements 42corresponding to the columns of the dot matrix. Accordingly, the dotdata for each line of image consists of 1728 bits (=216 bytes). Usually,the dot data are processed at one time for each page of image to bereproduced.

Each rotation of the photosensitive drum 30 corresponds to one page ofimage, and the scanner unit 34 is controlled to imagewise expose thedrum 30 along each scanning line according to 216 bytes of dot data.Each byte of the dot data is identified by the line number (representedby an address) and the byte number. Each byte corresponds to eightcolumns of the dot matrix.

The line number and the byte number of the dot data are designated by aRECORDING CONTROL routine according to a program stored in the programmemory 380, as illustrated in the flow chart of FIG. 32.

The routine of FIG. 32 uses two control constants K and M, which areboth positive integers. These control constants K, M are automaticallydetermined on the basis of the image resolution of the scanner unit 34of the present facsimile system (hereinafter referred to as "ownresolution") and the image resolution of the remote facsimile system 325(hereinafter referred to as "remote resolution"), and according to arelation table stored in the RELATION TABLE memory 389 as indicated inFIG. 31. The own resolution corresponds to the size of the pictureelements 42 of the dot matrix of the image to be reproduced by thepresent facsimile system. The remote resolution is the resolution of theoriginal image represented by the original image data received from theremote facsimile transmitter 325.

The size of the picture element 42 in the secondary scanning direction(in the direction of the column of the dot matrix) varies with the imageresolution as indicated below.

SUPER-FINE: 1/15.4 mm

FINE: 1/7.7 mm

STANDARD: 1/3.85 mm

For example, the size of the picture elements 42 in the secondaryscanning direction when the SUPER-FINE image resolution is selected isone half that when the FINE image resolution is selected. Therefore,when the own resolution is SUPER-FINE while the remote resolution isFINE, the size of the image reproduced on the present facsimile systemis reduced to a half that of the original image represented by thereceived original image data. To compensate for a difference between theown and remote resolutions, in this case, original image data for oneline of image should be used to reproduce two lines of the same images.To this end, the control constant K is set at "2". For the same reasons,the control constant K is set at "1" when the own and remote resolutionsare the same. When the own and remote resolutions are SUPER-FINE andSTANDARD, respectively, the constant K is set at "4".

The control constant M designates the degree of saving of the toner 50in the TONER-SAVE recording mode. The degree of saving of the tonerdecreases with an increase in the constant M. When the constant M is"2", the ratio of the number of lines to be reproduced according to theoriginal image data to the total number of the lines which include blanklines for saving the toner 50 is equal to 1/2. When the constant M is"4", the ratio is equal to 3/4. If the total number of lines is "4", inthis case, only one blank line is provided. In the present embodiment,each blank line is provided by rotating the photosensitive drum 30 bythe predetermined incremental angle corresponding to one line, withoutimagewise scanning of the drum 30. However, each blank line is formedaccording to a dummy dot data set whose bits are all "0".

Although the constant K may be determined independently of the constantM or depending upon the constant M, the present embodiment is adaptedsuch that the constant M is set at "2" in all cases independently of theconstant K and the own and remote image resolutions, as indicated inFIG. 31. Even when the own and remote resolutions are the same, theconstant M is set at "2", so that the recording is effected in theTONER-SAVE recording mode.

There will be described a recording operation in the NON-TONER-SAVINGrecording mode with the TONER-SAVE flag set at "0". In this case, anegative decision (NO) is obtained in step S85 of the routine of FIG.32, and all lines are recorded according to the original image data,more precisely, according to respective sets of dot data obtained fromthe encoded reception image data received from the remote transmitter325. In the flow chart of FIG. 32, "L" designates each line ofelectrostatic latent image formed on the photosensitive drum 30, but notthe line of an original image as represented by the corresponding set ofthe dot data. When the constant K is not "1", the two or more lines ofelectrostatic latent images are formed corresponding to one line of theoriginal image represented by a set of dot data. In the routine of FIG.32, the line number "L" and integers "m" and"n" are initially zeroed.

Each set of dot data representing a line of original image consists of216 bytes (8×216 bits=1728 bits) where the paper sheet 18 is an A4 sizesheet, and is designated by (n+1) represented by the respective address,as indicated in FIG. 30, where "n"=0, 1, 2, 3, . . . . This dot data set(n+1) is used for forming electrostatic latent image lines (K×n+1)through {K×(n+1)}. When the integer "n" is "0", the first dot data set(0+1) is used for the first (K×0+1) through K-th {K×(0+1)} lines ofelectrostatic latent images. When the integer "n" is "1", the second dotdata set (1+1) is used for the (K+1)th through 2K-th lines ofelectrostatic latent images.

The routine of FIG. 32 where the constant K is set at "4" will bedescribed by way of example.

The routine is initiated with step S81 to increment the line number L.In the first cycle of execution of the routine of FIG. 32, the linenumber L (initially set at "0") is incremented to "1". Then, the controlflow goes to step S82 to determine whether the line number L is equal to(Kn+1). Since the integer is initially set at "0", step S82 in the firstcycle of execution of the routine is to determine whether the numberline L is equal to (4×0+1), namely, equal to "1" or not. Therefore, anaffirmative decision (YES) is initially obtained in step S82, and thecontrol flow goes to step S83 to set the address A_(L) (=A1) of the linenumber L (first line of the electrostatic latent image) to (0000)corresponding to the (n+1)th line, namely, first line of the originalimage represented by the first set of the dot data. Thus, the first dotdata set designated by the address (0000) is retrieved. Step S83 isfollowed by S84 to increment the integer "n" and S85 to determinewhether the TONER SAVE flag is set at "1". In the present case where theflag is set at "0", a negative decision (NO) is obtained in step S85,and the control goes to step S86 to imagewise scan the photosensitivedrum 30 according to the first dot data set which consists of 216 bytes(Y1 through Y216) at the address (0000) as indicated in FIG. 30, wherebythe first line of electrostatic latent image is formed such that thelocal spots corresponding to the picture elements 42 arelaser-irradiated when the corresponding dot data bits are "1", and notlaser-irradiated when the dot data bits are "0", as indicated in FIG.18. As the drum 30 is imagewise scanned, the drum is rotated by thepredetermined incremental angle corresponding to one line.

The imagewise exposure of the photosensitive drum 30 by a laser beam isstarted a predetermined time after the horizontal synchronizing signalis generated, so that the retrieval of the appropriate dot data set issynchronized with the imagewise exposure of the photosensitive drum 30.The predetermined time indicated above corresponds to a dummy scanningarea which precedes the line of electrostatic latent image to be formedwithin a predetermined area corresponding to the width of the papersheet 18.

Upon completion of step S86, the control flow returns to step S81 toincrement the line number L to "2". Step S81 is followed by step S82 todetermine whether the line number L is equal to "5" (=4×1+1). In thiscase where the line number L is "2", a negative decision (NO) isobtained in step S82, and the control flow goes to step S87 to set theaddress A_(L) (=A2) of the second line of electrostatic latent image to(0000) corresponding to the n-th line, namely, first line of theoriginal image represented by the first set of the dot data. Thus, thefirst dot data set designated by the address (0000) is retrieved for thesecond line of electrostatic latent image, too. Then, the control flowgoes to step S85, and to step S86 to imagewise scan the drum 30 to formthe second line of electrostatic latent image according to the first dotdata set. Consequently, the second line of electrostatic latent image iscompletely the same as the first line of electrostatic latent image.

Similarly, the third and fourth lines of electrostatic latent image areformed according to the first dot data set, with the line number L setto "3" and "4".

When the line number L is incremented to "5" in step S81, an affirmativedecision (YES) is obtained in step S82, and the control flow goes tostep S83 in which the address A5 of the fifth line of electrostaticlatent image is set to (00D8) corresponding to the (n+1)th line of theoriginal image, namely, second line of the original image. Therefore,the second dot data set designated by the address (00D8) is retrieved,and the fifth line of electrostatic latent image is formed according tothe second dot data set in step S86. For the reasons described abovewith respect to the second through fourth lines of electrostatic latentimages, the sixth through eighth lines of electrostatic latent imagesare also formed according to the second dot data set designated by theaddress (00D8).

Thus, the first through eighth lines of electrostatic latent image areformed as indicated at 404 in FIG. 33, according to the first and seconddot data sets. Each of the four latent image lines "a" of the latentimage 404 is the same as the original image line "a" represented by thefirst dot data set, while each of the four latent image lines "b" of thelatent image 404 is the same as the original image line "b" representedby the second dot data set.

The photosensitive drum 30 is rotated at a speed corresponding to theown image resolution, that is, SUPER-FINE resolution, as theelectrostatic latent image is formed by the scanner unit 34.

While the electrostatic latent image 404 is formed where the controlconstant K is equal to "4", namely, where the own resolution isSUPER-FINE and the remote resolution is STANDARD, an electrostaticlatent image 406 is formed where the control constant K is equal to "1",namely, where the own and remote resolutions are both SUPER-FINE, forexample. An electrostatic latent image 408 is formed where the controlconstant K is equal to "2", namely, where the own resolution isSUPER-FINE while the remote resolution is FINE. Visible images to beformed on the paper sheet 18 correspond to the electrostatic latentimages 404, 406, 408.

The dot data sets used to activate the scanner unit 34 in theNON-TONER-SAVE mode as described above are referred to as the originalimage data or "non-toner-save image data".

Where the TONER SAVE flag is set at "1", every M-th line ofelectrostatic latent image is formed as a blank line (consisting of 1728white or non-imaged local spots). In other words, where the line numberis equal to (M×m+p), the scanner unit 34 is not supplied with any dotdata set, so that imagewise scanning is not effected for that linenumber (M×m+p), but the drum 30 is rotated by a predeterminedincremental angle corresponding to one line. That is, no local spots inthat line number (M×m+p) are irradiated by a scanning laser beam, as ifall bits of the dot data set for that line number were "0".

In the present specific example, the constant M is equal to "2" and thevalue "p" is also equal to "2". Since the constant M is "2", one of twosuccessive lines formed on the drum 30 is the blank line. Since thevalue "p" is "2", the first one of these two successive lines is theblank line.

When the line number L is "1", the dot data set designated by theaddress (0000) is retrieved in step S83, and the affirmative decision(YES) is obtained in step S85, since the TONER SAVE flag is set at "1".Consequently, step S88 is implemented to determine whether the linenumber L is equal to (Mm+2), namely, equal to "2" (2×0+2). As the linenumber L is currently "1", a negative decision (NO) is obtained in stepS88, and the control flow goes to step S86 to activate the scanner unit34 to form the first electrostatic latent image line according to thefirst dot data set.

When the line number L is incremented to "2", an affirmative decision(YES) is obtained in step S88, and the control flow goes to step S89 inwhich only the drum 30 is rotated by the incremental angle withoutactivation of the scanner unit according to any dot data set. Thus, noimagewise scanning is effected for the second line (L=2) of the firsttwo successive lines. A command to rotate the drum 30 by thepredetermined incremental angle in step S89 without imagewise scanningis considered to be a non-imaging data set for making the second lineblank. Step S89 is followed by step S90 to increment the integer "m" to"1".

When the line number L is "3", the negative decision (NO) is obtained instep S88, since the line number "3" is not equal to (2×1+2)=4. In thiscase, the scanner unit 34 is activated according to the first dot dataset. When the line number L is "4", the affirmative decision (YES) isobtained in step S88, and the drum 30 is rotated without imagewisescanning by the scanner unit 34. Then, the integer "m" is incremented to"2" in step S90.

When the line number L is "5", the second dot data set designated by theaddress (00D8) is retrieved in S83 because the affirmative decision(YES) is obtained in step S82. Since the negative decision (NO) isobtained in step S88, step S86 is implemented to activate the scannerunit 34 to form the fifth line of electrostatic latent image accordingto the second dot data set. When the line number L is then incrementedto "6", the affirmative decision (YES) is obtained in step S88, and thesixth line is made blank, with the drum 30 rotated without imagewisescanning according to the second dot data set.

With the routine repeatedly executed as described above, every secondline (second, fourth, sixth, etc.) is made the blank line, since thecontrol constant "M" is set at "2". These even-numbered lines may beconsidered as electrostatic latent image lines formed according to dotdata sets whose bits are all "0".

As a result, a latent image is formed on the drum 30 as indicated at 410in FIG. 34, according to the original image lines "a" and "b"represented by the first and second dot data sets. The latent image 410is developed into the corresponding visible image on the paper sheet 18.

The data used to form the latent image 410 in the TONER-SAVE recordingmode are referred to as "toner-save image data", which is different fromthe original image data.

In the case where the scanner unit 34 is operated in the TONER SAVErecording mode according to the toner-save image data, a suitable TONERSAVE marking 411 is provided at a right upper corner of the paper sheet18, as indicated in FIG. 35. The marking 411 indicates that the visibleimage on the sheet 18 has been recorded in the TONER SAVE recordingmode. This marking 411 is recorded according to the TONER SAVE MARKINGDATA GENERATION routine stored in the program memory 390 of the ROM 334.It is also noted that when the TONER SAVE recording mode is established,the TONER SAVE light 302 is illuminated on the operator's control panel14.

Although the recording on the paper sheet 18 according to the originalimage data received from the remote facsimile transmitter 325 has beendescribed above, the selective use of the TONER-SAVE or NON-TONER-SAVErecording mode according to the present invention is also applicable toa copying operation on the present facsimile system, on the basis of anoriginal image data which are obtained from the image reading device 66and which are stored in the TRANSMISSION IMAGE DATA memory 364. Usually,the image data in the memory 364 are used as image data to betransmitted to the remote facsimile receiver 325. However, the imagedata in the memory 364 may be used to make a copy of the original readby the image reading device 66.

When the copying operation as indicated above is effected, the TONERSAVE flag is set or reset according to a suitable routine stored in theROM 334, which does not use the IMPORTANT IMAGE DATA flags 1, 2 and 3 asused in the routine of FIGS. 23-25. That is, the TONER SAVE flag is seton the basis of the GRAY SCALE DATA flag, OPERATING CONDITION flag, etc.

In the copying operation, the OPERATING CONDITION flag is set and resetin the same manner as described above with respect to the facsimilereception recording on the basis of the image data received from theremote facsimile transmitter 325. Although the GRAY SCALE DATA flag isset and reset by the routine of FIG. 26 in the case of the facsimilereception recording, this flag used in the copying operation is set andreset, depending upon whether a GRAY SCALE mode has been established bymanipulation of the RESOLUTION key 320 and other switches on theoperator's control panel 14. The GRAY SCALE DATA flag is set when theGRAY SCALE mode has been established, and is reset when the GRAY SCALEmode has not bee established.

In the copying operation, the resolution set by the user is substitutedfor the remote resolution (image resolution of the remote facsimilesystem 325).

It will be understood from the foregoing description of the presentfacsimile system that selected entire lines of the dot matrix image aremade blank to save the consumption of the toner 50 in the TONER-SAVErecording mode. This arrangement permits easier data processing than inthe case where the toner save recording is effected by providing blanklocal spots at the selected picture element positions along each line ofthe dot matrix. Further, the toner-save image data are generated basedon the decoded image data in the form of the dot data representative ofthe original image, so that the toner-save image data represent atoner-save image which is recognizable as an image similar to theoriginal image.

Since the control constants K and M are determined depending upon theown resolution (resolution of the present facsimile system) and theremote resolution (resolution of the remote facsimile system 325, thetoner-save visible image has a suitable density and can be recognized asan image similar to the original image.

The TONER SAVE light 302 informs the user of the present facsimilesystem as to whether that the system is placed in the TONER-SAVErecording mode. This arrangement permits the user to know whether thereduced density of the visible image recorded on the paper sheet 18 isdue to the recording in the TONER-SAVE recording mode, or due toinsufficient amount of the toner 50 in the toner cartridge 120.

The TONER SAVE marking 411 recording on the paper sheet 18 permits thereader of the paper sheet 18 to know whether the recording on the sheet18 has been conducted in the TONER-SAVE or NON-TONER-SAVE recordingmode, even after a long time has passed after the recording.

It is important to note that the TONER SAVE flag is automatically set orreset on the basis of the degree of importance or type (gray scale dataor not) of the image data to be reproduced, and the operating conditionand environment of the facsimile system. That is, the user does not haveto manipulates a mode selector switch to select the TONER-SAVE orNON-TONER-SAVE recording mode. The automatic setting of the TONER SAVEflag assures selection of the TONER-SAVE recording mode as needed.

The user of the facsimile system does not have to know the importance,nature or type of the image data received, and does not have to checkthe operating condition or environment of the system, since the TONERSAVE flag is automatically controlled as described above.

Nevertheless, the user is provided with means for for manually selectingthe TONER-SAVE or NON-TONER-SAVE recording mode, namely, changing themode from the TONER-SAVE mode to the NON-TONER-SAVE mode or vice versa,depending upon the density of the actually formed image on the papersheet 18 and the TONER SAVE marking 411 on the sheet 18.

In the present embodiment, the developing device 48 including thescanner unit 34 constitutes a recording portion for recording an imageon the basis of original image data. The decoded image data in the formof dot data obtained from the encoded image data received from theremote facsimile system 325 serve as the original image data which arestored in original image data memory means in the form of the DECODEDRECEPTION IMAGE DATA memory 362. However, the encoded image data or dotdata may be considered to be the original image data. The encoded imagedata or decoded image data (dot data) are considered to be the primarydata of the facsimile data received from the remote facsimiletransmitter 325.

The toner-save image data used in the TONER-SAVE recording mode (withthe affirmative decision obtained in step S85) consist of the originaldot data sets (step S86), and the command (step S89) to rotate the drum30 by the predetermined incremental angle corresponding to one line,without imagewise scanning of the drum 30. Thus, a portion of thecontrol device 40 assigned to implement steps S85-S89 is considered asmeans for generating the toner-save image data, and as a toner-savecontrol portion for controlling the recording portion (developing device48) in the TONER-SAVE recording mode. The RELATION TABLE 389 and aportion of the control device 40 assigned to determine the controlconstants K and M on the basis of the own and remote resolutionscooperate to constitute means for determining the control constants.

A portion of the control device 40 assigned to implement steps S81-S85and S87 constitutes a non-toner-save control portion for controlling therecording portion (developing device 48) in the NON-TONER-SAVE recordingmode. The program memory 385 storing the TONER SAVE FLAG SETTING routineand a portion of the control device 40 assigned to execute this routineCooperate to constitute mode selecting means for selecting one of theTONER-SAVE recording mode and the NON-TONER-SAVE recording mode, ormeans for activating one of the non-toner-save control portion and thetoner-save control portion to control the recording portion (developingdevice 48) in the corresponding NON-TONER-SAVE or TONER-SAVE recordingmode.

It is also noted that the program memory 390 storing the TONER SAVEMARKING DATA GENERATION routine and a portion of the control device 40assigned to execute this routine cooperate to constitute a markingdevice for recording a marking on the sheet 18, which indicates therecording in the TONER-SAVE mode. The TONER SAVE light 302 and a portionof the control device assigned to control the light 302 depending uponthe TONER SAVE flag cooperate to constitute a display device forindicating the selection of the TONER-SAVE recording mode. The markingdevice and the display device constitute an indicator device forindicating the recording in the TONER-SAVE recording mode.

The residual toner amount sensor 142, humidity sensor 64 and paper sheetsensor 25 cooperate with the control device 40 to constitute respectivedevices for detecting the amount of the toner 50 remaining in the tonercartridge 120, detecting the operating environment of the facsimilesystem, and detecting a special paper sheet 18 (sheet 18 placed on themanual sheet insertion table 24). Further, the program memory 386storing the OPERATING CONDITION FLAG SETTING routine cooperates with aportion of the control device to execute this routine to constitute modeselector means for selecting the TONER-SAVE or NON-TONER-SAVE recordingmode depending upon the operating condition or environment of thefacsimile system.

It is further noted that step S32 of the GRAY SCALE FLAG SETTING routinestored in the program memory 388 and a portion of the control device 40assigned to implement this step S32 cooperate to constitute means fordetecting gray scale image data, and that steps S38-S40 of the GRAYSCALE FLAG SETTING routine and a portion of the control device 40 toimplement these steps S38-S40 cooperate to constitute mode selectormeans for selecting the TONER-SAVE or NON-TONER-SAVE recording mode,which mode selector means includes image data type determining means fordetermining the type of the image data, so that the recording mode isselected depending upon the determined type of the image data. Namely,the gray scale data representative of an image in a dither matrix areone type of the image data.

As indicated above, the facsimile data consist of image data as theprimary data, and the ancillary data which include: data indicative ofthe image resolution; data (stored in the memory 368) indicative of thefacsimile number of the remote facsimile transmitter 325 from whichimage data have been received; and data (stored in the memory 366)indicative of the facsimile number of the present facsimile system whichis designated by the call signal received from the remote facsimiletransmitter 325. The primary data include the encoded image data anddecoded image data (dot data). The memories 366 and 368 function asancillary data memory means for storing the ancillary data. Theancillary data memory means comprises remote party information memorymeans for storing remote party information including number-related dataindicative of (a) the distinctive ringing facsimile number of thepresent facsimile system which has been called by the remote facsimilesystem, and (b) the facsimile number of the remote facsimile system fromwhich the facsimile data have been received. The memory 370 serves asremote facsimile receiver number-related memory means for storing thefacsimile numbers of the remote facsimile receivers 325 to which thefacsimile data are highly expected to the transmitted. The CALL SIGNALPATTERN memory 392 serves as reception facsimile number-related memorymeans for storing number-related data indicative of the facsimilenumbers of the present facsimile system available for reception offacsimile data from the selected remote facsimile transmitters 325,which are highly expected to transmit important original image data.

The program memory 391 storing the COMMUNICATION RECORD OUTPUT routineand a portion of the control device 40 assigned to execute this routinecooperate to constitute record data generating means for generatingcommunication record data for producing a record of the facsimilecommunications between the present and remote facsimile systems.

The program memory 381 storing the IMPORTANT IMAGE DATA FLAG 1 SETTINGroutine and a portion of the control device 40 assigned to execute thisroutine cooperate to constitute importance determining means fordetermining the degree of importance of the received image datadepending upon the facsimile number of the present facsimile systemwhich is designated by the distinctive ringing call signal received fromthe remote facsimile transmitter 325. The program memory 382 storing theIMPORTANT IMAGE DATA FLAG 2 SETTING routine and a portion of the controldevice 40 assigned to execute this routine cooperate to constituteimportance determining means for determining the degree of importance ofthe received image data depending upon the facsimile number of theremote facsimile transmitter 325. These importance determining meansfunction as means for determining the importance of the received imagedata, on the basis of the data received from the remote facsimile system325.

It is also noted that the program memory 384 storing the COMMUNICATIONRECORD IMPORTANCE SETTING routine and a portion of the control device 40assigned to execute this routine cooperate to constitute means fordetermining that the communication record as the original image data hasa relatively low degree of importance. This means function as means fordetermining the degree of importance of the recording data on the basisof the nature or type of the recording data. A portion of the controldevice 40 assigned to set the TONER SAVE flag to "1" upon manipulationof the operator's control panel 14 to produce a communication recordconstitutes means for selecting the TONER-SAVE recording mode forproducing the communication record. This means may be considered toconstitute the mode selector means for selecting the TONER-SAVE orNON-TONER-SAVE recording mode depending upon the degree of importance ofthe subject matter of the image data or recording data.

In the illustrated embodiment described above, the CONDITION flag 1 isset to "1" to set the TONER SAVE flag to "1" for selecting theTONER-SAVE recording mode, when the amount of the toner 50 remaining inthe toner cartridge 120 is smaller than the predetermined threshold.However, the CONDITION flag 1 is reset to "0" to select theNON-TONER-SAVE recording mode when the residual toner amount is smallerthan the threshold. This arrangement prevents excessively low density ofthe recorded image which would occur due to the recording in theTONER-SAVE mode with a considerably small amount of the toner, andassures sufficiently clear recording of the image for a prolonged periodtime. In some situations, the quality of the recorded image is moreimportant than the prolongation of the life of the toner cartridge 120by reduction of the toner consumption.

While the IMPORTANT IMAGE DATA flags 1 and 2 are set to "1" to selectthe NON-TONER-SAVE recording mode where the remote facsimile system 325from which image data have been received is one of the predeterminedremote facsimile systems, these flags 1 and 2 may be reset to "0" toselect the TONER-SAVE recording mode in the above case, if thepredetermined remote facsimile systems are those remote parties who tendto transmit facsimile data whose subject matters can be relativelyeasily understood or recognized by the user of the present facsimilesystem, or those remote parties whom the user may easily contact toclarify the subject matter or content of the received facsimile data.

It is possible to inhibit the recording in the TONER-SAVE mode for adesired portion of a page of image, for example, an upper part of thefirst page of the received original image data, which generally containsinformation that identifies the remote facsimile system 325. Forinstance, the upper part of the first page for which the recording inthe TONER-SAVE mode is inhibited may be between the upper edge of thepage and a line about 100 mm below the upper edge. In this case, therecording in that upper part is effected in the NON-TONER-SAVE mode evenif the remote facsimile system 325 from which the facsimile data havebeen received is one of the predetermined remote parties.

The TONER SAVE flag may be set or reset to select the TONER-SAVE orNON-TONER-SAVE mode, according to different rules for different parts ofthe same page of image, for example, according to different rulesrelating to the GRAY SCALE DATA flag.

In the illustrated embodiment of FIG. 23, the TONER SAVE flag is set to"1" only where the IMPORTANT IMAGE DATA flag 3, GRAY SCALE DATA flag,OPERATING CONDITION flag and the other flags are all set at "0".However, the TONER SAVE flag may be set to "1" when the negativedecision (NO) is obtained in at least one of steps S1-S3 or when thenumber of the flags for which the negative decision is obtained in stepsS1-S3 is larger than a predetermined value.

The TONER SAVE flag may be set and reset depending upon only theIMPORTANT IMAGE DATA flags 1 and 2.

The routines of FIGS. 23-28 for the TONER SAVE flag may be modified asneeded.

In the embodiment of FIG. 26, the GRAY SCALE DATA flag is set on thebasis of the dot data bits. However, the encoded image data as receivedfrom the remote facsimile transmitter 325 may be used in the routine ofFIG. 26, in place of the binary dot data. For instance, the GRAY SCALEDATA flag may be set on the basis of the number of the run-length codesin the compressed coded image data.

While the predetermined number "s" used in the routine of FIG. 26 isequal to "3" to check the first three dot data sets, the number "s" maybe "4" or more. Although the number Ns is compared with thepredetermined threshold in step S33 for each of the dot data sets, thetotal number Ns of all the dot data sets in question may be comparedwith a predetermined threshold in setting or resetting the GRAY SCALEDATA flag.

The routine of FIG. 26 is based on the fact that gray scale data ofdither matrix generally have a relatively large number of changes ofadjacent data bits. In this connection, it is noted that image datarepresenting a minute image (e.g., an image consisting of relativelysmall characters) also have a relatively large number of changes ofadjacent data bits. Therefore, the routine of FIG. 26 may be used todetermine or detect the minuteness of the image.

While the TONER SAVE light 302 as indicated in FIG. 19 is turned on toindicate the selection of the TONER-SAVE recording mode, the display 300may be adapted to provide an indication of the selection of theTONER-SAVE recording mode, as indicated in FIG. 41. The indication maybe provided as long as the TONER-SAVE recording mode is established, oronly during an image recording operation in the TONER-SAVE mode.

The TONER SAVE light 302 or the indication of the TONER-SAVE recordingmode on the display 300 is not essential, particularly where the TONERSAVE marking 411 is recorded on the paper sheet 18 or the recording inthe TONER SAVE mode can be recognized from the image recorded on thepaper sheet 18.

In the illustrated embodiment, the control constant M determining theratio of saving of the toner in the TONER-SAVE recording mode isdetermined on the basis of the resolutions of the present and remotefacsimile systems. However, the control constant M may be determined onthe basis of the operating conditions (e.g., detected residual toneramount) of the present facsimile system.

For example, the constant M is automatically selected according to apredetermined relationship between the detected residual amount of thetoner 50 and the constant M. The relationship may be formulated suchthat the constant M is changed continuously with the detected residualtoner amount, or in steps corresponding to predetermined two ore moreranges of the residual toner amount.

If the constant M is reduced as the residual toner amount is reduced,the toner saving ratio is increased as the residual toner amount isreduced. This arrangement prevents an unexpected sudden change from theNON-TONER-SAVE mode to the TONER-SAVE mode when the residual toneramount becomes smaller than a predetermined threshold, but permits acontinuous or stepped increase of the toner saving ratio.

The constant M may be increased as the residual toner amount is reduced.The residual toner amount sensor 142 may be modified as needed. Forexample, the agitating arm 204 and wiper 206 may be disposed so as toextend toward the agitating portion 202 of the third agitating member122.

The control constants K and M may be determined on the basis of both ofthe own and remote resolutions and the detected residual toner amount,or independently of the resolutions and/or residual toner amount. In theembodiment of FIG. 32, step S88 is adapted to determine whether the linenumber L is equal to (Mm+2). However, the variable (Mm+2) may bereplaced by (Mm+1) or (Mm+3), so that the first line of two successivelines or the third lines of three successive lines is made blank in theTONER-SAVE recording mode, for example.

In the present embodiment wherein the constant M is set at "2" where theown resolution is SUPER-FINE while the remote resolution is STANDARD, asindicated in the table of FIG. 31, the constant may be set at "4" inthis case, so that two or three lines of four successive lines may bemade blank. For instance, the second and third lines, or the second andfourth lines may be made blank, or alternatively, the second throughfourth lines may be made blank.

Where the constant M is "4" while the second line of the four successivelines is made blank, the affirmative decision (YES is obtained in stepS88 in the routine of FIG. 32 when the line number L is "2", "6" and"10", so that these lines are made blank, as indicated in FIG. 36 inwhich an electrostatic latent image (or visible image) formed isindicated at 412.

In the case where the second, third and fourth lines of four successivelines are made blank, the RECORDING CONTROL routine of FIG. 32 ismodified as illustrated in the flow chart of FIG. 37.

Steps S101 through S106 of the routine of FIG. 37 are identical withsteps S81-S85 and S87 of the routine of FIG. 32. Where the line number Lis "1", the negative decision (NO) is obtained in step S107, since theline number L is not equal to (4×0+2)=2. Therefore, the control flowgoes to steps S108 and S109 to determine whether the line number L isequal to "3" or "4". The negative decision (NO) is obtained in thesesteps S108, S109, whereby the dot data set designated by the address(0000) is supplied to the scanner unit 34 to image wise scan thephotosensitive drum 30.

Where the line number L is incremented to "2", the affirmative decision(YES is obtained in step S107, and the control flow goes to step S111 inwhich the drum 30 is rotted by the incremental angle without imagewisescanning.

Where the line number L is "3", the affirmative decision (YES) isobtained in step S108, and the control flow goes to step S112 to rotatethe drum 30 by the incremental angle without imagewise scanning. Wherethe line number L is "4", the affirmative decision (YES) is obtained instep S109, and step S113 is implemented to rotate the drum 30 withoutimagewise scanning. Step S113 is followed by step S114 to increment theinteger "m". Thus, the routine of FIG. 37 is adapted such that thesecond, third and fourth lines of the four successive lines are madeblank without imagewise scanning of the drum 30.

Where the line number L is incremented to "5", the affirmative decision(YES) is obtained in step S102, and the second dot data set designatedby the address (00D8) corresponding to the second line of the dot datais retrieved in step S103. Since the negative decision (NO) is obtainedin steps S107-S109, the control flow goes to step S110 to activate thescanner unit 34 according to the second dot data set.

Where the line number L is "6", "7" or "8", the scanner unit 34 is notactivated according to the second dot data set (steps S111-S113), andthe sixth through eighth lines are made blank.

Thus, the line numbers "1", "5", "9", . . . are formed according to therespective dot data sets, while the line numbers "2" through "4" and "6"through "8", . . . are made blank, whereby an electrostatic latent imageor visible image 414 as indicated in FIG. 38 is formed on the drum 30 orpaper sheet 18. In the present embodiment of FIGS. 37 and 38, the tonersaving ratio is higher than in the embodiment of FIGS. 32, 34 and 36 inwhich only one of successive lines is made blank.

Although the embodiment of FIGS. 37-38 to inhibit imagewise scanning ofthe drum 30 for the three lines of the four successive lines, it ispossible to designate one of the four successive lines for which thedrum 30 is imagewise scanned. The function achieved by the routine ofFIG. 37 can be achieved by modifying the routine of FIG. 32 such thatthe variable (Mm+2) used in step S88 is changed to (Mm+1) and steps S86and S89 are switched so that step S86 follows step S88 if theaffirmative decision is obtained in step S88 while step S89 follows stepS88 when the negative decision is obtained in step S88. In this modifiedroutine, the first line of the four successive lines is formed byimagewise scanning of the drum 30.

Thus, where "P" represents the number of successive lines correspondingto each original dot data set while "p" (p<P) represents the number ofthe blank line or lines formed without imagewise scanning of the drum30, the designation of the number p is practically the same as thedesignation of the number (P-p) of the lines formed by imagewisescanning of the drum 30 according to the respective dot data sets.

In step S89 of FIG. 32 and steps S111-S113 of FIG. 37, the drum 30 ismerely rotated by the incremental angle corresponding to one line,without imagewise scanning by the scanner unit according to theappropriate dot data set. so that the line in question is made blank inthe TONER-SAVE recording mode. However, steps S89 and S111-S113 may bemodified so that the drum 30 is scanned by the scanner unit 34 accordingto a dummy dot data set whose bits are all "0". The dummy dot data setis considered to be the non-imaging data set for forming a blank line.

In the above modification, a batch of dot data as indicated in FIG. 30generated by the encoder/decoder circuit 344 on the basis of thereceived batch of encoded image data is modified as indicated in FIG.39. Namely, a dummy dot data set designated by an address (0000) isadded as the zeroth dot data set. The dummy dot data set consists of1728 bits which are all "0".

Where the dummy dot data set is used, the recording operation iscontrolled in a routine as illustrated in the flow chart of FIG. 40,wherein the control constants K and M are set at "4" and "2",respectively, and the integers "L", "m", "n" are initially set at "0",as in the routine of FIG. 32

Since the recording in the NON-TONER-SAVE mode in the routine of FIG. 40is the same as that in the routine of FIG. 32, only the recording in theTONER-SAVE mode in the routine of FIG. 40 will be described.

Where the line number L is "1", the affirmative decision (YES) isobtained in step S202, and the control flow goes to step S203 in whichthe first dot data set designated by the address (00D8) corresponding tothe first line (A1) is retrieved. Step S203 is followed by step S204 toincrement the integer "n", and step S205 in which the drum 30 isimagewise scanned according to the first dot data set.

When the line number L is incremented to "2", the negative decision (NO)is obtained in step S202 while the affirmative decision (YES) isobtained in step S206, whereby step S207 is implemented to determinewhether the line number L is equal to (Mm+2), namely, (2×0+2)=2. Sincethe affirmative decision (YES) is obtained in step S207, the controlflow goes to step S208 in which the zeroth dot data set, that is, thedummy dot data set designated by the address (0000) is retrieved for thesecond line. Step S208 is followed by step S209 to increment the integer"m", and step S205 in which the drum 30 is not only rotated by theincremental angle, but also scanned by the scanner unit 34 according tothe retrieved zeroth or dummy dot data set whose bits are "0".Accordingly, no local spots are irradiated by the laser beam along thesecond line, and the second line is made blank.

When the line number L is "3", the negative decision (NO) is obtained instep S202 and the affirmative decision (YES) is obtained in step S206,and the negative decision (NO) is obtained in step s207, whereby thefirst dot data set designated by the address (00D8) is retrieved in stepS210, and the drum 30 is imagewise scanned along the third lineaccording to the retrieved first dot data set.

When the line number L is "4", the affirmative decision (YES) isobtained in step S207, and the zeroth or dummy dot data set is retrievedin step S208, whereby the fourth line is made blank. With the routine ofFIG. 40 repeatedly executed, the image 410 as indicated in FIG. 34 isformed in the TONER-SAVE recording mode.

The embodiment of FIGS. 39-40 also permits easy data processing due tothe scanning according to the dummy dot data set for each blank line.

While the recording operation according to a batch of image datareceived from the remote facsimile transmitter 325 has been describedwith respect to the various embodiments, the present facsimile systemmay be operated to process binary image data obtained from the lineimage sensor 84 of the image reading device 66, by a routine similar tothat of FIG. 40, to thereby obtain dot data for toner-save recording,which dot data are encoded into coded image data to be transmitted tothe remote facsimile receiver 325.

Image data (dot data) for toner-saving may be obtained by controllingthe image reading device 66 such that the image reading by the lineimage sensor 84 is not effected for the lines to be recorded in blank.

The toner-saving image data generated by the image reading device 66 areeffective particularly where the present facsimile system is used as acopying machine to copy an original image read by the device 66, orwhere the device 66 is used in an exclusive copying machine. However,the toner-saving image data generated by the device 66 may beadvantageously used for toner saving recording in the remote facsimilereceiver 325 when the remote facsimile receiver 325 is found to beplaced in the TONER-SAVE recording mode. On the basis of informationstored in the present facsimile system, or information received from theremote facsimile system 325, the present facsimile system may determinethat the remote facsimile receiver 325 is placed in the TONER-SAVErecording mode. Alternatively, the user of the present facsimile systemmay determine that the remote facsimile receiver 325 is in theTONER-SAVE recording mode.

In the above case, the toner-saving image data are converted into codedimage data to be sent to the remote facsimile receiver 325, whichconverts the coded image data into the toner-saving image data in theform of dot data, so that the recording is effected in the TONER-SAVEmode in the remote facsimile receiver 325.

The present facsimile system may deal with coded image data which aregenerated by MH or MR method by the remote facsimile system 325.

Although the embodiments illustrated above are all adapted to insertblank lines parallel to the scanning direction of the scanner unit 34 inthe TONER-SAVE recording mode, it is possible to insert blank columnsparallel to the rotating direction of the drum 30 in the TONER-SAVErecording mode. This arrangement also assures easier data processingthan in the conventional arrangement which requires a determination asto whether an image dot is formed at each local spot in a line or columnof the dot matrix.

In the case of insertion of the blank columns, decoded image data or dotdata corresponding to one page of image are first generated from thecorresponding coded image data received from the remote facsimiletransmitter, and are then processed so that the all dot data bitscorresponding to the picture elements in each of the selected blankcolumns are "0". However, the dot data bits corresponding to the pictureelements in all the selected blank columns are zeroed each time the dotdata set for each line is supplied to the scanner unit 34.

Further, both blank lines and blank columns may be provided in theTONER-SAVE recording mode. In this case, the processing of the dot datafor the blank lines and the processing for the blank columns may beeffected simultaneously or at different times. For instance, theprocessing for the blank columns is effected for dot data correspondingto one page of image, while the processing for the blank lines iseffected when the dot data sets are supplied to the scanner unit 34.

Referring to FIGS. 42-53, there will be described a further embodimentof the present invention as applied to a recording apparatus connectedto external computers.

The recording apparatus has a main body 500 having a front upper portioncovered by a front cover 502, as shown in FIG. 42. To the left of thefront cover 502, there are provided control switches and indicatorlights, which include a TONER SAVE light 504. This light 504 is turnedon when the TONER SAVE flag is set at "1". In a rear upper portion ofthe main body 500, there is provided a cassette holder 506 in which apaper cassette 508 is removable received, as shown in FIG. 43. A stackof paper sheets 18 is accommodated in the paper cassette 508. Theapparatus incorporates an automatic sheet feeder for delivering thepaper sheets 18 one after another from the cassette 508.

The cassette holder 506 has an upper wall which serves as a manual sheetinsertion table 510 on which the sheet 18 is manually placed. The sheet18 placed on the table 510 is also fed by the automatic sheet feeder.

The front cover 502 is pivotable about pins 512 provided on a frontportion of the main body 500. The front cover 502 has a closed positionof FIG. 42 and an open position of FIG. 43. In the closed position, thefront cover 502 covers the front upper portion of the main body 500. Inthe open position, the front cover 506 serves as a sheet tray onto whichthe recorded sheets 18 are ejected.

The present recording device includes the scanner unit 34 and thedeveloping device 48 which are constructed as described above withrespect to the facsimile system of FIGS. 1-41. The same referencenumerals as used in FIGS. 1-41 are used to identify the correspondingelements of the present apparatus.

The recording apparatus has a control device 520 as shown in FIG. 44,which incorporates a CPU 522, a RAM 524, a ROM 526, an NVRAM 528, aparallel/serial converter circuit 342, an encoder/decoder circuit 532and an interface 534. The TONER SAVE light 504 indicated above isconnected to the control device 520. Two or more external computers areconnected to the control device 520. However, only one external computer536 is shown in FIG. 44, in the interest of simplification.

The encoder/decoder circuit 532 functions to decode coded character datareceived from the external computer 536, into dot data according topattern data stored in a CHARACTER PATTERN DATA memory 540 of the ROM526. The dot data define various characters in a matrix of dots. Forinstance, character "A: is defined in a dot matrix consisting of 48 rowsand 48 columns. The rows corresponds to the lines of the dot matrix usedin the facsimile system of FIGS. 1-41. In the present recordingapparatus, the dot data are formulated to provide the SUPER-FINE imageresolution.

As indicated in FIG. 45, the RAM 524 includes a CHARACTER CODE DATAmemory 542, an EXTERNAL DOT DATA memory 543, an INTERNAL DOT DATA memory544, and AUXILIARY DATA memory 546.

The CHARACTER CODE DATA memory 542 stores the coded character datareceived from the external computer 536, while the EXTERNAL DOT DATAmemory 543 stores dot data received from the external computer 536. Thedot data stored in the memory 543 will be referred to as "external dotdata" as distinguished from "internal dot data" stored in the INTERNALDOT DATA memory 544, which are obtained by conversion of the codedcharacter data by the encoder/decoder circuit 532 as mentioned above.Generally, graphical representations or images other than characters arereceived from the external computer 536, in the form of dot data("external dot data").

The AUXILIARY DATA memory 546 stores auxiliary data received from theexternal computer 536, namely, data other than the coded character dataand external dot data. For example, the auxiliary data include:character size data indicative of the size of the characters representedby the coded character data; mode data indicative of the selection ofthe TONER-SAVE or NON-TONER-SAVE recording mode; and toner save ratiodata indicative of the ratio of saving of the toner 50 in the TONER-SAVErecording mode. In the present apparatus, three toner save ratios areavailable in the TONER-SAVE recording mode.

As indicated in FIG. 46, the ROM 526 includes the CHARACTER PATTERN DATAmemory 540 indicated above, and the OPERATING CONDITION FLAG SETTINGprogram memory 386 and the TONER SAVE MARKING DATA GENERATION programmemory 390 which have been discussed with respect to the facsimilesystem of FIGS. 1-41. The ROM 526 further includes a RECORDING CONTROLprogram memory 550, a CHARACTER SIZE FLAG SETTING program memory 551, aSPECIAL CHARACTER RATIO FLAG SETTING program memory 552, a TONER SAVEFLAG SETTING program memory 554, and RELATION TABLE memory 555.

As shown in FIG. 47, the NVRAM 528 includes a CONDITION flag 1indicating whether the amount of the toner 50 remaining in the tonercartridge 120 is smaller than the threshold value.

There will be described an operation of the present recording apparatus.Those aspects of the operation which are similar to those of thefacsimile system described above will not be described to avoidredundancy of description.

The TONER SAVE flag is set and reset by a routine stored in the TONERSAVE FLAG SETTING program memory 554, as illustrated in the flow chartof FIG. 48.

The routine of FIG. 48 is initiated with step S301 to determine whetherthe CHARACTER SIZE flag is set at "1". If an affirmative decision (YES)is obtained in step S301, the control goes to step S302 to determinewhether the SPECIAL CHARACTER RATIO flag is set at "1". If anaffirmative decision (YES) is obtained in step S302, the control goes tostep S303 whether the other flags are all set at "1". If the affirmativedecision is obtained in all of the steps S301-S303, the control flowgoes to step S304 to set the TONER SAVE flag to "1" to select theTONER-SAVE recording mode. If a negative decision (NO) Is obtained inany one of the steps S301-S303, the control flow goes to step S304 toreset the TONER SAVE flag to "0" to select the NON-TONER-SAVE recordingmode.

The CHARACTER SIZE flag is set to "1" when the character size designatedby character size data included in the auxiliary data stored in theAUXILIARY DATA memory 546 is larger than a predetermined threshold.Thus, relatively large characters are recorded in the TONER-SAVE mode.The reduced density of the image dots of the characters recorded in theTONER-SAVE mode does not significantly reduce the legibility of thecharacters. The

The CHARACTER SIZE flag is set or reset by a routine stored in theCHARACTER SIZE FLAG SETTING program memory 551, as illustrated in theflow chart of FIG. 49. The routine is initiated with step S321 in whichthe character size data are read out from the AUXILIARY DATA memory 546.Step S321 is followed by step S322 to determine whether the charactersize represented by the character size data is larger than a thresholdvalue. If the character size is not larger than the threshold value, anegative decision (NO) is obtained in step S322, and the control flowgoes to step S323 to reset the TONER SAVE flag to "0". If the charactersize is larger than the threshold value, an affirmative decision (YES)is obtained in step S322, and the control flow goes to step S324 to setthe TONER SAVE flag to "1".

The SPECIAL CHARACTER RATIO flag is reset to "0" when the ratio(hereinafter referred to as "special character ratio") of the number ofall the characters represented by the character data to the number ofthe numerals, symbols and other special characters other than theletters is larger than a threshold value. Where the character data areASCII code data, the characters are represented by respective eight-bitcodes, and the special characters may be detected on the basis of theASCII codes.

Usually, most of a batch of character data consist of codes representingletters such as alphabetic letters and Japanese and Chinese letters, orrepresent a descriptive part of an image. Generally, a descriptivestatement consisting of the alphabetic letters can be understood fromthe context, even if the density of image dots of the letters iscomparatively low due to the recording in the TONER-SAVE mode. On theother hand, the special characters such as the numerals and symbolscannot be easily recognized if those special characters are more or lessillegible due to the reduced density of image dots of the recordedcharacters. In view of the above, the SPECIAL CHARACTER RATIO is resetto "0" to select the NON-TONER-SAVE recording mode if the ratio of thespecial character ratio is larger than a threshold value.

If the threshold value is close to zero, the SPECIAL CHARACTER RATIOflag is set to "0" when a batch of character data includes a few specialcharacters. If the threshold value is larger than 0.1 or larger than0.3, for example, the character data are considered to include arelatively large number of mathematical equations and/or tables, and theSPECIAL CHARACTER RATIO flag is reset to "0".

The SPECIAL CHARACTER RATIO flag is set and reset by a routine stored inthe SPECIAL CHARACTER RATIO FLAG SETTING program memory 552. The routineis initiated with step S331 to count the total number D of charactercodes included in the character data for one page or one line. Step S331is followed by step S332 to count the number C of the character codesrepresentative of the special characters, and calculate the specialcharacter ratio C/D. Then, the control flow goes to step S333 todetermine whether the special character ratio C/D is larger than apredetermined threshold value. If the special character ratio C/D is notlarger than the threshold value, a negative decision (NO) is obtained instep S333, and the control flow goes to step S334 to set the SPECIALCHARACTER RATIO flag to "1". If the ration C/D is larger than thethreshold value, an affirmative decision (YES) is obtained in step S335,and the control flow goes to step S335 to reset the SPECIAL CHARACTERRATIO flag to "0".

The other flags indicated above includes the CONDITION flags 1, 3 and 3which have been described above by reference to the flow chart of FIG.27, and other flags which are set or reset according to toner saveinformation received from the external computer 536. If the receivedtoner save information indicates the selection of the TONER-SAVErecording mode, the TONER SAVE flag is set to "1".

In the present recording apparatus, the scanner unit 34 is operated scanthe drum 30 along parallel lines, according to the internal dot datastored in the INTERNAL DOT DATA memory 544 as shown in FIG. 52, anddepending upon the state of the TONER SAVE flag. The recording operationis effected by a routine stored in the RECORDING CONTROL program memory550, as illustrated in the flow chart of FIG. 51.

The control constant M and integer "p" used in step S355 of the routineof FIG. 51 are determined according to a relation table stored in theRELATION TABLE memory 555, and on the basis of the auxiliary datareceived from the external computer 536. As indicated above, the presentembodiment is adapted to use three toner save ratios in the TONER-SAVErecording mode. The constant M is set at "4" irrespective of the tonersave ratio. The relation table is formulated to set the integer "p" to"2" if the smallest toner save ratio is selected, to "2" and "4" if theintermediate toner save ratio is selected, and to "2", "3" and "4" ifthe largest toner save ratio is selected.

There will be described an operation by reference to the flow chart ofFIG. 51 where the constant M and integer p are set at "4" and "2",respectively. the line number L and the integer "m" are initiallyzeroed.

When the line number L is "1", the address (0000) of the INTERNAL DOTDATA memory 544 is selected in step S352, for the first line. Then, stepS353 is implemented to determine whether the TONER SAVE flag is set at"1". If not, step S354 is implemented to imagewise scan the drum 30according to the dot data set at the selected address (0000) for thefirst line. As the line number L is incremented, the imagewise scanningalong the successive lines L are effected according to the respectivedot data sets at the addresses A_(L), whereby the original image ornon-toner-save image is formed as indicated at 562 in FIG. 53.

If the TONER-SAVE flag is set at "1", the affirmative decision (YES) isobtained in step S353, and the control flow goes to step S355 todetermine whether the line number L is equal to (Mm+2). Where the linenumber L is "1", the negative decision is obtained in step S355, andstep S354 is implemented to form the first line according to the firstdot data set.

When the line number L is incremented to "2", the affirmative decisionis obtained in step S355, and the control flow goes to step S356 inwhich the drum 30 is rotated by the incremental angle without imagewisescanning according to the second dot data set for the second line,whereby the second line is made blank. When the line number L is "3",step S354 is implemented to imagewise scan the drum according to thethird dot data set at the address for the third line. When the linenumber L is "4", the affirmative decision is again obtained in stepS355, and the control flow goes to step S356, whereby the fourth line ismade blank. A toner-save image recorded in the TONER-SAVE recording modeincludes the two blank lines, as indicated at 564 in FIG. 53.

In the present embodiment described above, the coded character data andthe external dot data which are received from the external computer 536,and the internal dot data obtained by conversion from the codedcharacter data are stored in the respective different memories 542, 543and 544. The special characters such as the numerals and symbols may bedetected on the basis of the character codes of the character data, incalculating the special character ratio C/D used to set or reset theTONER SAVE flag.

Further, the TONER SAVE flag is set or reset depending upon thecharacter size data stored as part of the auxiliary data stored in theAUXILIARY DATA memory 546.

Although the present embodiment of FIGS. 42-53 is adapted to determinethe control constant M depending upon the auxiliary data received fromthe external computer 536, the constant M may be determined on the basisof the special character ratio C/D. In this instance, a relation tablerepresentative of a relationship between the constant M and the ratioC/D is stored in the ROM 526. The constant M may be determined dependingupon the character size. In this case, a relation table representativeof a relationship between the constant M and the character size isstored in the ROM 526.

The present recording apparatus may be used in conjunction with a singleexternal computer 536.

It will be understood from the above description of the presentembodiment that the coded character data correspond to the originalimage data representative of an original image to be reproduced in theNON-TONER-SAVE mode. The memory 542 serves as memory means for storingthe coded image data. The encoder/decoder circuit 532 functions as meansfor converting the coded character data into binary dot data (decodedimage data), while a portion of the control device 520 assigned toimplement steps S301 and S302 provides mode selector means for selectingthe NON-TONER-SAFE or TONER-SAVE recording mode depending upon the typeof the original image data.

Further, a portion of the control device 520 assigned to implement stepS321 constitutes means for determining the size of the charactersrepresented by the coded character data, while a portion of the controldevice 520 assigned to implement steps S322-s324 constitutes modeselector means for selecting the NON-TONER-SAVE or TONER-SAVE recordingmode depending upon the minuteness of characters represented by theoriginal image data, more specifically, depending upon the charactersize.

It is also noted that portions of the control device 520 assigned toimplement steps S332 and S333 constitute means for detecting the specialcharacters, and means for determining the special character ratio C/D,respectively. A portion of the control device 520 assigned to implementsteps S334-S336 constitutes mode selector means for selecting therecording mode depending upon the special character ratio C/D.

It is further noted that the RELATION TABLE memory 555 and the CPU 522of the control device 520 cooperate to constitute means for determiningthe control constant M on the basis of the auxiliary data received fromthe external computer 536.

It is to be understood that the present invention may be embodied withvarious other changes, modifications and improvements, which may occurto those skilled in the art, without departing from the spirit and scopeof the invention defined in the following claims.

What is claimed is:
 1. A recording apparatus comprising:a recordingportion for effecting a recording operation on a recording medium in amatrix of dots by selective application of a toner to local spots onsaid medium, according to original image data representative of anoriginal image to be reproduced, said local spots corresponding topicture elements of said dot matrix; a non-toner-save control portionfor controlling said recording portion according to said original imagedata to form said original image in a non-toner-save recording mode; atoner-save control portion for controlling said recording portionaccording to a toner-save image data to form a toner-save image in atoner-save recording mode, said toner-save image having a lower densityof image dots than said original image and being recognizable as animage similar to the original image, said toner-save control portiongenerating said toner-save image data on the basis of said originalimage data; and mode selector means for activating one of saidnon-toner-save control portion and said toner-save control portion toselect a corresponding one of said non-toner-save and toner-saverecording modes, on the basis of a type of said original image data. 2.A recording apparatus according to claim 1, wherein said mode selectormeans comprises selecting means for selecting said non-toner-saverecording mode when said original image data are gray scale data.
 3. Arecording apparatus according to claim 2, wherein said mode selectormeans comprises gray scale data recognizing means for recognizing saidoriginal image data as said gray scale data which represent saidoriginal image in a dither matrix, said selecting means selecting saidnon-toner-save recording mode when said gray scale data recognizingmeans recognizes said original image data as said gray scale data.
 4. Arecording apparatus according to claim 2, wherein said original imagedata are dot data comprising data bits representative of presence orabsence of image dots at said local spots corresponding to said pictureelements of said dot matrix, and said selecting means comprises meansfor recognizing said original image data as said gray scale data if thenumber of changes of adjacent ones of said data bits of said dot dataper unit volume of said dot data is larger than a predeterminedthreshold.
 5. A recording apparatus according to claim 4, furthercomprising image data generating means for generating said dot data onthe basis of said original image data.
 6. A recording apparatusaccording to claim 1, wherein said matrix of dots is defined by aplurality of parallel lines extending in a first direction, and aplurality of parallel columns extending in a second directionintersecting said first direction, said toner-save control portiongenerating said toner-save image data which include non-imaging datasets for inhibiting the application of said toner to all of said localspots which are arranged along selected ones of said parallel linesand/or said parallel columns of said matrix of dots, so that saidtoner-save image is partially defined by blank lines and/or blankcolumns of local spots which correspond to said non-imaging data sets,respectively, said toner-save control portion controlling said recordingportion in the toner-save recording mode, according to the toner-saveimage data including the non-imaging data sets, said blank lines andsaid blank columns appearing in said toner-save lines at respectivelines and columns represented by at least one of equations L=M×m+p,where "L" represents said blank lines and blank columns, "M" is aninteger not smaller than "2", "m" is an integer which increases from "0"in increment of "1", and "p" is an integer betweeen "1" (inclusive) and"M" (inclusive).
 7. A recording apparatus according to claim 6, whereinsaid mode selector means comprises image minuteness detecting means fordetermining whether a degree of minuteness of said original imagerepresented by said original image data is larger than a predeterminedthreshold value, said mode selector means activating said non-toner-savecontrol portion if said image minuteness detecting means determines thatsaid degree of minuteness of said original image is larger than saidpredetermined threshold value.
 8. A recording apparatus according toclaim 7, wherein said toner-save control portion determines at least oneof a value of said integer "M" and the number of said at least one ofequations L=M×m+p, on the basis of said degree of minuteness of theoriginal image determined by said image minuteness detecting means.
 9. Arecording apparatus according to claim 8, wherein said toner-savecontrol portion determines said at least one of said number of said atleast one integer and said each value of said at least one integer, onthe basis of toner save information received from an external devicefrom which said original image data are received.
 10. A recordingapparatus according to claim 1, wherein said mode selector meanscomprises image minuteness detecting means for determining whether adegree of minuteness of said original image represented by said originalimage data is larger than a predetermined threshold value, said modeselector means activating said non-toner-save control portion if saidimage minuteness detecting means determines that said degree ofiminuteness of said original image is larger than said predeterminedthreshold value.
 11. A recording apparatus according to claim 1, whereinsaid matrix of dots is defined by a plurality of parallel linesextending in a firext direction, and a plurality of parallel columnsextending in a second direction intersecting said first direction, saidtoner-save control portion generating said toner-save image data whichinclude non-imaging data sets for inhibiting the application of saidtoner to all of said local spots which are arranged along selected onesof said parallel lines and/or said parallel columns of said matrix ofdots, so that said toner-save image is partially defined by blank linesand/or blank columns of local spots which correspond to said non-imagingdata sets, respectively, said blank lines and said blank columnsappearing in said toner-save lines at respective lines and columnsrepresented by at least one of equations L=M×m+p, where "L" representsaid blank lines and blank columns, "M" is an integer not smaller than"2", "m" is an integer which increases from "0" in increment of "1", and"p" is an integer betweeen "1" (inclusive) and "M" (inclusive), saidtoner control portion determines at least one of a value of said integer"M" and the number of said at least one equation L=M×m+p, on the basisof toner save information received from an external device from whichsaid original image data are received.
 12. A recording apparatusaccording to claim 1, further comprising character data memory means forstoring coded character data as said original image data, and image datagenerating means for generating binary image data on the basis of saidcoded character data, said non-toner-save control means controlling saidrecording means according to said binary image data in saidnon-toner-save recording mode, and wherein said mode selector meanscomprises character recognizing means for recognizing a type ofcharacters as represented by said coded character data, said modeselector means activating one of said non-toner-save control portion andsaid toner-save control portion, depending upon the type of saidcharacters recognized by said character recognizing means.
 13. Arecording apparatus according to claim 12, wherein said characterrecognizing means comprises character size determining means fordetermining whether a size of said characters is larger than apredetermined threshold value, and said mode selector means activatessaid toner-save control portion if said size of the characters isdetermined to be larger than said threshold value.
 14. A recordingapparatus according to claim 12, wherein said character recognizingmeans comprises special character detecting means for detecting specialcharacters other than letters, in said characters as represented by saidcoded character data.
 15. A recording apparatus according to claim 14,wherein said special character recognizing means comprises ratiodetermining means for determining a special character ratio which is aratio of a number of said special characters to a total number of saidcharacters as represented by said coded character data, said modeselector means activating said non-toner-save control portion if saidspecial character ratio is larger than a predetermined threshold value.16. A recording apparatus according to claim 1, wherein said modeselector means comprises image data type determining means fordetermining said type of said original image data, and importancedetermining means for determining a degree of importance of a subjectmatter of said original image data, said mode selector means activatingone of said non-toner-save control portion and said toner-save controlportion, on the basis of said degree of importance determined by saidimportance determining means, as well as on the basis of the type ofsaid original image data determined by said image data type determiningmeans.
 17. A recording apparatus according to claim 16, furthercomprising facsimile data memory means for storing facsimile data, andimage data generating means for generating said original image data onthe basis of said facsimile data, said facsimile data comprising primarydata, and ancillary data associated with facsimile communication betweenthe recording apparatus and a remote facsimile system from which saidrecording apparatus receives said facsimile data, said facsimile datamemory means comprising ancillary data memory means for storing saidancillary data of said facsimile data, and primary data memory means forstoring said primary data, said image data generating means comprisingmeans for generating said original image data on the basis of saidprimary data,and wherein said ancillary data memory means comprisesremote party information memory means for storing remote partyinformation indicative of said remote facsimile system, said importancedetermining means determining said degree of importance of the subjectmatter of said original image data, on the basis of said remote partyinformation.
 18. A recording apparatus according to claim 17, whereinsaid mode selector means further comprises remote facsimile receivernumber memory means for storing number data indicative of a facsimilenumber of each of at least one remote facsimile receiver to whichfacsimile data are expected to be transmitted from the recordingapparatus, said remote party information comprises number dataindicative of a facsimile number of said remote facsimile system fromwhich said facsimile data have been received by the recording apparatus,said importance determining means determining said degree of importanceof the subject matter of the original image data, by comparing saidfacsimile number of said remote facsimile system stored in said remoteparty information memory means with said facsimile number of each ofsaid at least one remote facsimile receiver stored in said remotefacsimile receiver number memory means.
 19. A recording apparatusaccording to claim 1, wherein said mode selector means comprises imagedata type determining means for determining said type of said originalimage data, and operating condition detecting means for detecting atleast one operating condition of the recording apparatus, said modeselector means activating one of said non-toner-save control portion andsaid toner-save control portion, on the basis of said at least oneoperating condition detected by said operating condition detectingmeans, as well as said degree of importance determined by saidimportance determining means.
 20. A recording apparatus according toclaim 19, wherein said recording portion comprises a toner supply foraccommodating said toner, and said operating condition detecting meanscomprises a toner amount sensor for sensing an amount of said tonerremaining in said toner supply, said mode selector means activating oneof said non-toner-save control portion and said toner-save controlportion depending upon whether said amount of the toner remaining insaid toner supply is smaller than a predetermined threshold, as well ason the basis of said degree of importance.
 21. A recording apparatusaccording to claim 1, further comprising an indicator device forindicating that said toner-save recording mode is selected.
 22. Arecording apparatus according to claim 21, wherein said indicator devicecomprises a display for providing an indication that said toner-saverecording mode is selected.
 23. A recording apparatus according to claim21, wherein said indicator device comprises a marking device foroperating said recording portion to form a marking on said recordingmedium, said marking indicating that said toner-save image has beenrecorded in said toner-save recording mode.